a review of groundwater status, challenges, and...

Preprint - do not cite - 1

A Review of Groundwater status, challenges, and 1

research needs in the Kathmandu Valley, Nepal 2

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Soni M. Pradhanang 4 City University of New York, Institute for Sustainable Cities, New York, NY, USA 5 [email protected] 6

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Suresh Das Shrestha 8 Tribhuvan University, Department of Geology, Kathmandu, Nepal 9

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Tammo S. Steenhuis 11 Department of Biological and Environmental Engineering 12 Cornell University, Ithaca, NY, USA 13

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Corresponding Author: 36

Soni M. Pradhanang, City University of New York, Institute for Sustainable Cities. New York, 37 NY, [email protected] 38

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mailto:[email protected]

mailto:[email protected]


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ABSTRACT 2

3 Drinking water quality and quantity has been one of the biggest concerns in water sector in The 4 Kathmandu Valley, the biggest urban center in Nepal. Aquifer characteristics and groundwater 5 flow properties are complex. They vary laterally and, vertically and temporally creating 6

dynamic, interdependent systems that can be affected in unpredictable and irreversible ways as a 7 result of rapid development and mismanagement. Over extraction of groundwater in the Valley 8 has resulted in groundwater depletion. The problems related to groundwater quality range from 9 contamination from sewage line, septic failures, and open pit latrines, leaching from landfill 10 sites, and direct disposal of domestic and industrial wastes to the surface water. Studies have 11

shown that both the quantity and quality of groundwater in The Kathmandu Valley is in immense 12 threat that needs immediate attention. The research, development and management of 13

groundwater resources are still emerging. Priorities need to be set up for effective mapping and 14

monitoring of this resource by developing research and management plans. The goal of this 15

paper is to summarize status of groundwater quantity and quality, challenges and research needs 16 in The Kathmandu Valley based on available literature. 17 18

19 20

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Keywords: Aquifer, extraction, water quality, mapping, development. 22


1. INTRODUCTION 1

Groundwater resources play a major role in ensuring livelihood security across the world and 2

can provide a uniquely reliable source of high-quality water for human uses. Not all groundwater 3

is accessible. In many cases it is too deep or too salty to be used. In other case the ground water 4

is soils with little permeability. In cases that groundwater is available; it is perceived by many, as 5

inexhaustible resource. Therefore, in many places in the semi arid and arid areas of the world, 6

ground water tables are dropping with rates of 1 meter per year or more. Base flows in streams, 7

wetlands and surface vegetation are in many cases dependent on groundwater levels and 8

discharges. Change in those levels or changes in groundwater quality induce cascading effects 9

through terrestrial and aquatic ecosystems. In China, for example that had once many beautiful 10

rivers, ground water withdrawal caused these rivers to disappear or in some cases are filled with 11

the waste water from the cities. The same is true for Kansas, USA where rivers are starting to 12

disappear. 13

The ability to access groundwater plays a major role in increasing incomes and reducing 14

risks in agricultural economy (Moench et al., 2003). The depletion of groundwater is taken as a 15

first indicator of water scarcity (Shah and Indu, 2004). Drinking water quality and quantity has 16

been one of the biggest concerns in water sector in Kathmandu Valley, the biggest urban center 17

in Nepal (Cresswell et al. 2001; Pathak et al. 2009). The Kathmandu valley covers about 327 18

km2 of 664 km

2 surface watershed areas in the central Nepal with average altitude of 1350 m 19

above mean sea level. Annual precipitation in the valley is around 1755 mm, 80% of which is 20

from monsoon rain that spans from June to September (Pandey et al. 2010). Recharge to the 21

region’s main aquifer has been variously reported to be 15 million m3/yr (i.e., 165 mm/yr) 22

(Binnie and Partners 1989) to less than 5 million m3/yr (i.e., 55 mm/yr) (Gautam and Rao 1991). 23

Recharge to the deep confined aquifer, however, is suggested to be < 80,000 m3/yr (1mm/yr) 24


(Gautam and Rao 1991).The study by CES (1992) reported that almost 50% of the valley’s water 1

supply is derived from groundwater. The extraction rate is reported to be 20 million m3/yr. 2

Large inconsistencies in reported recharge and extraction rates warrant a standard protocol of 3

research. 4

The problems related to groundwater range from contamination from sewage line, septic 5

failures, open pit latrines (Jha et al. 1997), leaching from landfill sites, and direct disposal of 6

domestic and industrial wastes to the surface water (Khadka 1992; Karn and Harada 2001). 7

Surface water in Kathmandu Valley is highly polluted due to unregulated disposal of domestic 8

and industrial wastes. Such haphazard waste disposal systems cause contamination of shallow 9

aquifers. About 50% of the water supply in KTM is from groundwater systems that consist of 10

both shallow and deep aquifers (Jha et al 1997; Khatiwada et al. 2002). Variety of systems such 11

as tube wells, dug wells, and stone spouts constitute major mechanisms of groundwater use, due 12

to insufficient supply of surface water for both drinking and non-drinking uses. These systems 13

are also known to be contaminated by pollutants and pathogens (Table 1). 14

The population of KTM valley in 2001 was 1.6 million with a projected growth rate of 15

5% (MOPE, 2000; ADB, 2004; Dixit and Upadhyaya 2005) (Figure 1). Various other 16

organizations have different projections for the population of the Valley. After the inception of 17

municipal system in 1970s, which promoted use of surface water and deep aquifer tube wells and 18

shallow wells, many communities abandoned other sources of water which include traditional 19

stone spouts, dug wells and shallow aquifer tube wells (Khadka 1993; Warner et al. 2008). 20

However, the study conducted by Brown and Watkins (1994) reported that almost 20% of the 21

population of greater Kathmandu still rely on stone spouts during much of their year for their 22

water supply. 23


Year

1990 2000 2010 2020 2030

Po

pu

lati

on

in

mil

lio

ns

0.0

2.0

4.0

6.0

MOPE Census

BDS Design

SAPI Phase II

KUKL service area

1

Figure 1. Population census and projection for Kathmandu Valley [ Kathmandu Valley Census and 2 Projection (MOPE, 2000); Bulk Distribution System (BDS) Design Projection ; Special Assistance for 3 Project Implementation (SAPI) Phase II Projection; and Kathmandu Upatyaka Khanepani Limited 4 (KUKL) service area (~650 sq. km).[Source: ADB (2006)]. 5

The water demand of increasing population cannot be met by current supply from municipal 6

corporations (Dixit and Upadhyaya 2005). The inadequate and inefficient supply systems of 7

municipal corporations have led the population at large to supplement their water supply by 8

tapping into traditional water sources, i.e., stone spouts (Shrestha et al. 1996). Unfortunately 9

many stone spouts are now converted into temporary refuse dumps that need proper 10

rehabilitation. 11

The objective of this article is to present current status of groundwater both quantity and 12

quality, in Kathmandu Valley based on available literature and reports. Compilation of past 13

researches, methodologies and major findings that are relevant to ground water systems in 14

Kathmandu Valley is presented in Table 1 and discussed in following sections. 15


2. VULNERABILTY ASSESSMENT 1

2

The groundwater of Kathmandu Valley is under immense pressure as it is being heavily 3

utilized for both drinking and non-drinking purposes. Although groundwater overexploitation is 4

recognized as a serious problem (Cresswell et al. 2001), until mid 1990s, ground water resource 5

development received greater attention. The approaches of ground water resource development 6

coupled with monitoring, management and research is still developing. There are number of 7

researches that address the potential impacts of groundwater overuse on both quantity and 8

quality (Table 1), however, such researches are usually bound through contractual agreements to 9

keep data confidential from public access. Availability of such information will not only help to 10

develop scenario on groundwater use spatially and temporally, but also allow researchers to 11

evaluate vulnerability of groundwater usage addressing availability and water quality. Potential 12

dangers to drinking water sources, water quality and its availability are some indicators that are 13

considered for this study. 14

2.1 Mapping Groundwater Resources: 15

Conventional approaches to understanding groundwater resources involve geological 16

provinces describing broad physical characteristics of regional geological systems. These maps 17

describing the physical settings in which groundwater accumulates and modes need to be further 18

disaggregated to make them useful for local situations. The first step to understand the 19

vulnerability of groundwater system is to develop boundary maps and identify potential problem 20

areas. 21

Within the unconsolidated sediment of the Kathmandu Valley, there are two major aquifers 22

that provide locals with potable drinking water (Figure 2). The upper aquifer is composed of 23


quaternary arkosic sand, with some discontinuous, interbedded silt and clay of the Patan and 1

Thimi Formations (Yoshida and Igarashi 1984). The surficial sediments that compose the upper 2

aquifer are underlain by an aquitard of interbedded black clay and lignite that reaches up to 200m 3

in thickness in the western valley. The Pliocene sand-and-gravel, with interbedded lignite, peat 4

and clay lies beneath the clay aquitard and constitutes the deeper confined aquifer used by 5

several hotels, private companies and municipalities (Jha et al. 1997). 6

7

Figure 2. Map of Kathmandy Valley showing geological formation and ground water districts. 8


Table 1. Some relevant peer reviewed literature on Groundwater studies in The Kathmandu Valley. 1

Authors Objective of Research Methods Major Findings

Cresswell, R. G et

al., 2001

Quantification of groundwater

recharge rates and residence times

Radioisotope study Current recharge rate is about 5 to 15 mm/year

contributing 40,000 to 1.2 million m3/year to

the groundwater. Current extraction rate is 20

times of this amount and reserves will be used

up within 100 years at current rate of

extraction.

Dixit A. and

Upadhya M. 2005

Summarize existing knowledge on

groundwater conditions and identify

potentials for development

Compilation of relevant literature

and analysis

Substantial opportunity may exist for increasing

municipal supplies by conjunctive management

of surface and groundwater sources including

direct and indirect recharge and rainwater

harvesting.

Pattanayak S K.

and Yang J-C.

2005

Test the coping costs and stated

preferences for willingness to pay

for improved services

Household Survey of 1500

randomly sampled households;

develop profile of sample

households.

Coping costs arise from behaviors such as 1)

collecting, treating, storing and purchasing, 2)

are equivalent to 1% of current incomes, 3) are

lower than the willingness to pay, and 4) vary

across household with different socio-economic

backgrounds.

Villholth K G. and

Sharma B. 2006

Present major issues related to

groundwater in South and South

East Asia

Summary of literature To tackle the problem of groundwater

depletion, there is a need to integrate

environmental, social and economic factors

Effective groundwater resource management

requires an optimum balancing of the

increasing demands of water and land users

with the long-term maintenance of the complex

natural resource.

Gurung, J. et al.,

2007

Examine geochemistry of the

Kathmandu aquifer sediments, the

elution behavior of arsenic(As) and

evaluate the mechanism causing

mobilization of As in groundwater

Elution analysis to determine

potential leaching of As from the

aquifer sediment

Arsenic concentration in the sediments of

Kathmandu Valley average 8mg/kg, similar to

typical modern sediments (5-10mg/kg). The

mobilization of As in the Kathmandu Valley is

mainly related to change in the redox

conditions resulting from iron oxide rich sediment along with high organic content.


Table 1. Contd…


Kannel et al. 2007 The assessment of variation of water

quality, classification of monitoring

networks and identification of

sources

Water quality analysis of

important physical, chemical and

biological parameters

Upstream river water qualities in the rural areas

are affected mostly due to sewage disposal and

transport of fertilizers and manure applied to

agricultural fields. Urban water is mostly

polluted due to untreated municipal sewage and

can have impacts on shallow aquifers.

Warner et al. 2008 Identify common drinking water

contaminants; compare water quality

between sources; evaluate

relationship between water quality

parameters and site characteristics.

Water sampling (115 samples)

prior to monsoon season and

laboratory analyses for bacterial

contamination, inorganic

pollutants and heavy metals;

Household surveys using

questionnaire; statistical analyses

using non-parametric statistics.

Pathogens (coliform, both total and fecal) were

found in 72% of the water sampled. Nitrate-N

and ammonium-N exceeded the Nepali

guidelines for 45% of the samples, arsenic and

mercury exceeded WHO standards for 10% of

the samples.

Pathak, D. R. et

al., 2009

Development of groundwater

vulnerability map

GIS based DRASTIC model;

sensitivity analysis

The GIS based aquifer vulnerability map was

developed which is used to reflect an aquifer’s

inherent capacity to become contaminated

based on pollution index. The resulting range of

groundwater pollution potential index values

extended from 59 to 205. The vulnerability

index of Kathmandu indicated high

susceptibility to contaminations.

Chapagain et al.,

2010

Assess the current state of water

quality and identify the major

factors affecting water quality of

deep groundwater in the Valley

both.

Physico-chemical analysis of

major cations and anions;

Principal Component Analyses,

Factor Analyses and Cluster

Analyses of all water quality

parameters.

The groundwater in the valley is classified as

Ca-HCO3 and (Na+ K)- HCO3 types with

concentration of NH4+-N, Pb, As, Fe, Cd found

at most of the sampling locations. Water quality

of deep groundwater is affected primarily

related to hydrogeochemical properties and less

to the human activities.


Table 1 Contd…


Kannel et al. 2010 Evaluation of seasonal variations of

water qualities of Bagmati River.

Multivariate statistical analysis Seasonal variation in water quality were observed

especially for parameters such as, temperature,

DO, EC, COD, Cl, Ca, alkalinity, PO4-P,and TP.

Pandey et al., 2010 Develop a systematic knowledgebase

of the Kathmandu Valley’s

groundwater environment by

separating both natural and social

systems, analyzing their extent and

interrelationships.

Indicator that reflect valley’s

groundwater environment based on

review of published and

unpublished reports, papers, and

data.

The indicators show that the anthropogenic

factors are major drivers that exert pressures on

groundwater environment. Over-exploitation of

groundwater has lowered the groundwater levels

and raised concerns on risks of land subsidence in

area with high compressible clay and silt layers.

Pant B R. 2010 Assess quality of groundwater in the

Kathmandu Valley.

Groundwater samples from shallow,

deep-tube wells from October to

December 2004 were analyzed for

physical, chemical and biological

properties.

The groundwater in the Valley were found to be

contaminated with iron (1.5-1.9 mg/L) and

coliform bacteria (129 CFU/100 mL and 148

CFU/100 mL in tube well and deep well

respectively). Study showed high electrical

conductivity and turbidity.


Based on the hydrologic formation of various characteristics including river deposits, the

Kathmandu Valley is divided into three groundwater districts(Figure 2) a) northern, b) central,

and c) southern districts(JICA 1990). The northern groundwater district is composed of

unconsolidated highly permeable materials, which are about 60m thick and forms the main

aquifer in the valley. The coarse sediments are interbedded with fine impermeable sediments at

many places. This area is categorized to have relatively good recharge capacity. The central

district comprises of impermeable stiff black clay (sometimes ~200m thick), along with lignite

deposits and underlying layer of unconsolidated coarse sediment deposits of low permeability.

Existence of soluble methane gas in this area indicates stagnant aquifer condition. This area is

categorized to have low recharge capacity due to thick impermeable layers. The geologic

formations of the southern district consist primarily of thick impermeable clay and low

permeable base gravel. The aquifer in this area is known to be less developed (Pathak et al.

2009). According to the sedimentary development, the area suitable for recharging aquifers is

located mainly in the northern part of the valley and along the rivers. In the southern part

recharge is restricted to the areas along the gravel fans near the hillside. Detailed investigation on

this boundary is necessary or future researches. Until this is fully resolved pumping of this part

of the aquifer should be restricted.

Wide spread silty lacustrine deposits that are usually fine grained control groundwater

recharge for shallow aquifers in the Valley. The aquifer is interbedded with the impermeable

clay and prevents easy access of percolating rainwater to the aquifers. Most of the annual

precipitation falls during monsoon from June to September, but runs off quickly as surface flow

and is not sustained during the dry season. Streams of the Kathmandu valley receive some water

from the shallow aquifer after the monsoon season (Kharel et al. 1998). Recharge of the deep


aquifer occurs in the northeast part of Kathmandu Valley where the thick confining unit of clay

is not present (Figure 2).

Figure 3. Cross section through the Kathmandu Valley, with vertical exaggeration, adapted from

Jha et al. 1997 and Creswell et al. 2001

Pathak et al. (2009) developed groundwater aquifer vulnerability map by incorporating

the major hydro-geological factors that affect and control groundwater contamination. They used

the United States Environmental Protection Agency (EPA) approved groundwater vulnerability

analysis method called DRASTIC (Aller et al. 1987). The maps produced from such researches

are extremely valuable and serve as important resource to begin further impacts and vulnerability

assessments. In addition, such maps may be used for planning and predictive management of

groundwater resources. There are not many works that have focused on delineating groundwater

boundary and mapping of sub-surface groundwater systems. The lack of literature in this regard

is a clear indication that there is a need for research and development of mapping ground water

resources in Kathmandu Valley.

Stagnant Zone


2.2 Water Resource Issues:

The challenge associated with groundwater resource in Kathmandu valley is that there is

an over-exploitation of the resource in some parts of the Valley, whereas some areas have

relatively low levels of extractions. The study by Metcalf and Eddy (2000) showed that there was

a drop in pumping water level from 9 m to 68 m over the few years. The total sustainable

withdrawal of groundwater from the valley’s aquifers is approximately 0.0263 million m3 /d

(Stanley 1994), and increased to 0.0586 million m3 /d by 2000 (Metcalf and Eddy 2000).

However, it is unclear whether this withdrawal rate is representative of the shallow or deep

aquifers. One might be able to pump a lot from the shallow aquifer if there is sufficient rainfall to

fill up each year, given that the surface has good infiltration capacity.

Pandey et al. (2010) conducted a study to estimate groundwater storage potential in

Kathmandu Valley. They reported that the total extraction was less than 0.04 million m3/yr in

early 1970s, which went up to around 12.2 million m3/yr in late 1980s with another 90% increase

in late 1990s consistent with the findings of HMG (2004) (Figure 4). The study also classified

the period from 1970s to late 1990s as 1) early 1970s as the baseline situation where

groundwater availability was high with less being supplied to the public, 2) early 1980s as the

low impact period with inception of groundwater development and extraction systems, 3) mid

and late 1980s as the period when NWSC started well fields and impacts of extraction became

visible, 4) early 1990s when number of private wells increased and impacts increased, and 5) late

1990s as the period where haphazard pumping occurred resulting in groundwater table to decline

considerably.


Systems

NWSCHotels

PrivateDomestic

Government InstitutionsEmbassy

Gro

un

dw

ate

r E

xtr

acti

on

(m

3/d

)

0

5000

10000

24000

Shallow well

Deep Well

Dug Well

Figure 4. Groundwater extraction rate in The Kathmandu Valley for different systems from NWSC ( Nepal Water Supply Corporation currently known as Kathmandu Upatyaka Khanepani Limited) to other uses such as hotels, domestic uses, and institutions. [Source: HMG , 2004].

They also conducted a systematic knowledgebase study of the Kathmandu Valley’s

groundwater environment by separating both natural and social systems, analyzing their extent

and interrelationships. Their study concluded that the indicators show that the anthropogenic

factors are major drivers that exert pressures on groundwater environment. Over-exploitation of

groundwater has lowered the groundwater levels and raised concerns on risks of land subsidence

in area with high compressible clay and silt layers. This does not necessary mean that the

pumping should entirely focus on shallow aquifer systems.

Deep tube wells are the main means of extracting groundwater for use in the water supply

system. The study conducted by Asian Development Bank (2004) showed that out of 73 existing

deep tube-wells only ~74% were in operation. Most of the tube wells’ electro-mechanical parts

were considered to be in non operable condition with flow meters missing or broken. Tube wells

were used to be operated only in the dry season in order to supplement reducing surface water


sources, but, due to demand exceeding supply, the general public is now forced to use this

alternative source of water supply even during wet seasons. Deep wells usually have a very slow

recharge capacity. Further studies need to be done to explore other sources of groundwater

systems.

Table 2. Groundwater storage potential in municipalities of Kathmandu Valley

Municipality Area

(km2)

Potential Groundwater

Storage (million m3)

Population

Density

(2001)

Storage Area

(million m3/km

2)

Storage per

Capita

(m3)

Shallow

Aquifer

Deep

Aquifer

Total

Kathmandu 49.9 313.80 31.48 345.28 8445.4 6.9 819.6

Lalitpur 15.2 32.27 12.22 44.49 7617.7 2.9 384.0

Bhaktapur 6.4 9.44 11.71 21.15 9654.9 3.3 344.4

Madhyapur

Thimi

11.2 46.62 6.49 53.11 2862.1 4.8 1661.2

Kirtipur 14.6 0.0 16.71 16.71 2145.0 1.1 533.2

Source: Pandey et al., 2010

Cresswell et al. (2001) suggested that the basin’s deep aquifer has been confined for the

past 200,000 to 400,000 years. They also reported that recharge from the surrounding hills

contributes to the water budget of the deep aquifer, but at the rate that is very small relative to the

rate of removal of water by pumping. The study further estimated that at least 20 times the

amount of recharge is actually being pumped from these deep aquifers and suggested that

groundwater resource will be depleted below present extraction levels within 100 years. This

analysis might hold truth for the current situation. The extrapolation of the numbers to distant

years might need more research that focus on how recharge capacity of shallow aquifer is

affected through pumping. More infiltration take place, if more water is withdrawn resulting in

less flow downstream and less water flowing to the Terai region.


The primary basis for assessment of groundwater is based on the relationship between

pumping and annual replenishment which again is based on the aquifer characteristics. The

aquifer is the natural unit within which groundwater occurs. Aquifer characteristics, such as

storage and transmissivity are not being studied well. The geological diversity in Kathmandu

Valley warrants detailed study on characteristics and behavior of aquifers which primarily dictate

the approaches to managing groundwater resources and addressing vulnerability at local level.

Groundwater flow is slow and governed by hydraulic gradient and the conductive capacity of the

material through which the water is flowing. Excessive pumping of groundwater may change

natural hydraulic gradient and affect both groundwater flow patterns and the natural gradients

and recharge within an aquifer. As a result, even if water levels return to their original elevation

when pumping ceases, the migration of lower quality groundwater or surface water into the

aquifer system can occur (Burke and Moench, 2000). These reports however do not differentiate

between shallow and deep aquifers and their recharge capacity. The shallow aquifer will be

recharged but the deeper under the clay layer will not. Moreover it is not Darcy’s law in the

shallow aquifer that determines the recharge but it is the water balance at the surface. The flow

from the recharge area of the deep area near the valley wall to under the aquitard may be

explained by Darcy’s law. For the deep aquifer the permeability over the aquitard is too small to

provide sufficient water.

Another important factor that changes water level is vegetation cover. Forest and

vegetation cover has been long recognized as a major factor influencing run-off, infiltration and

evapotranspiration from shallow water tables (Dingman, 2002). Although Kathmandu Valley is

surrounded by forested hills, the valley itself does not have vegetation cover. The high rate of

urbanization has increased impervious surface that contributes to no infiltration and high runoff.


The message is thus clear; there is definite evidence on increased pressure on aquifers and the

race to abstract groundwater through wells and pumps to meet the demands of growing

population. The impervious surface created from building, infrastructures and roads lowers the

infiltration rate reducing water that can be otherwise stored in shallow aquifers. Researches that

address issues of effect of urbanization on infiltration rates will provide insights on

understanding groundwater dynamics in Kathmandu Valley which is undergoing dramatic

urbanization.

Aquifer depletion or overdraft occurs when groundwater is withdrawn at greater rate than

it can actually recharge. Groundwater in an unconfined aquifer fills the pores in the soil above

and this helps support it. When groundwater is withdrawn at a greater rate than it can be

replenished, the soil becomes compacted and subsides. Subsidence of ground surface will be

increase with increase in groundwater depletion, springs and seeps, decreasing water yield in

streams and rivers. Wetlands may dry due to decrease in water table depth. Vulnerability to

groundwater contamination increases with increased demand and pressure in this resource.

Developments should therefore, avoid or minimize disturbance to the extent, depth, or

hydrological balance of groundwater and wetlands.

2.3 Water Quality Issues:

The question of safety of the level of groundwater development in Kathmandu Valley can

be approached from another angle –that of water quality. Even while the Valley might be in

marginal situation in terms of quantitative availability of groundwater, but it has a high incidence

of water quality problems as indicated by researches (Table 1). The studies conducted by Jha et

al. (1997) showed that the concentration of ammonium-N (NH4-N), even in the deep well is

above the World Health Organization (WHO) standards Table 2). Other studies (JICA 1990;


Khatiwada et al. 2002; JICA/ENPHO 2005) have reported the occurrence of high levels of

ammonia, nitrate and E. coli in shallow aquifer in Kathmandu Valley. Chapagain et al. (2010)

used multivariate statistical analyses of water quality from 42 deep wells of Kathmandu Valley.

The major water quality variables such as NH4+-N, Fe, Pb, As, and Cd exceeded the World

Health Organization (WHO) standards for drinking water (Table 2) for most of the samples. The

water quality of deep groundwater however, is less influenced directly by human activities and

affected mostly from the natural hydro-chemical environment. Groundwater quality studies by

Pant (2010) showed higher iron and coliform content in all the samples tested. Other physical

parameters such as electrical conductivity and turbidity were found to be 875 µS/cm and 55 NTU

respectively exceeding the WHO limits for drinking water. The geochemical analysis of fluvio-

lacustrine aquifer sediments of the Kathmandu Valley was studied by Gurung et al. (2007) to

assess arsenic mobilization. Elution test of 15 sediment core samples showed that the greater

amounts of As are eluted from the fine sediments at varying rates. They attributed the As

contamination of groundwater to the redox condition and high organic content of underlying

sediments. Groundwater resources are particularly vulnerable to a build-up of arsenic because of

their interaction with arsenic bearing aquifers (Panthi et al. 2006). Arsenic is mobilized

preferentially under reducing conditions, but oxidizing groundwater with high pH and alkalinity

are also vulnerable.

Karn and Harada (2001) reported that Kathmandu generates ~272, 000 kg/day of solid

waste, of which less than 60% (i.e., ~ 150,000 to 190,000 kg/day) are collected. With

deteriorating management systems and political instability, the collection of domestic and

industrial waste might have gone even less than the earlier estimates. There are several landfill

sites that are located near the river banks that contain highly permeable sediment beds (Shrestha


et al. 1999). The waste water treatment system for both domestic and industrial wastes is not

enough and effective. In such circumstances, direct disposal of waste into the nearby rivers often

lead to the deterioration of surface water systems and even groundwater in the valley. Often

groundwater wells are located in the agricultural fields. Manure, fertilizers, and herbicides spread

in agricultural lands may eventually reach shallow aquifer systems contaminating them with

excess coliform, phosphorus, nitrogen and other organic compounds that can have health

implications. The wide extent of on-site sanitation septic tank systems and poor disposal of

septage pollutes shallow groundwater. Deeper groundwater is being over-extracted and

extraction is unsustainable. It is estimated that there are over 10,000 hand dug well which are

used to supplement the KUKL water supply (Dixit and Upadhyaya, 2005). Biological

contamination problems causing enteric diseases are present throughout the country and

probably constitute one of the major problems of concern. However, no clear estimates are

available on the impact of this problem. It must be noted, however, that this summary is based on

available data for the valley and represents only the tip of the iceberg of water quality problems.

At present, there are 21 water treatment plants (WTPs) in the system with a total

treatment capacity of about 0.085 million m3/d treating surface water and groundwater due to

high iron content and other pollutants. The largest is at Mahankal Chaur with a treatment

capacity of 9.9 million m3/yr and the smallest is at Kuleswor with a treatment capacity of 0.04

million m3/yr. Most of the WTPs are in poor condition and none has operational flow meters or

properly operating chlorination equipment (ADB, 2004). Given the waste disposal practices and

breadth of contamination sources, a broad examination of possible contaminants from sewage,

agriculture, and industry is deemed necessary. Pollutants such as nitrates, phosphorus, pathogens

need to be monitored at a regular basis. Beyond the inherent vulnerability of aquifers to


contamination, much depends on the nature of pollutant sources. Contaminant behavior varies

greatly with respect to the specific transport properties in each aquifer system. In addition, the

range of contaminant types is increasing as new products appear in effluent disposal and land

application.

Table 3. National Drinking Water Quality Standards, 2062 and National Drinking Water Quality

Standard Implementation Guideline, 2062 Year: 2063 (B.S.) Government of Nepal, Ministry of Land

Reform and Management Singhadurbar, Kathmandu, Nepal

Parameter Unit Maximum Concentration Limit Maximum Concentration

Limit

National Drinking Water

Quality Standards

WHO Drinking Water Quality

Standards

pH pH units 6.5-8.5a No guideline

Specific Conductance mS/cm 1.5

NO3-N mg/L 11.3b 50.0 for total nitrogen

NH3-N mg/L 1.24c

SO42-

mg/L 250 500.0

Al mg/L 0.2

As mg/L 0.05 0.01

Ca mg/L 200

Cd mg/L 0.003 0.003

Cu mg/L 1 2.0

Cr mg/L 0.05 0.05

Fe mg/L 0.3 No Guideline

Pb mg/L 0.01 0.01

Mn mg/L 0.2 0.05

Hg mg/L 0.001 0.001

Zn mg/L 3 3.0

E.coli bacteria CFU/100 ml 0 0.0

Total Coliform Bacteria CFU/100 ml 0 0.0

a Levels are the minimum to the maximum b Based on NO3- standard of 50 mg/L

c Based on NH3 standard of 1.5 mg/L CFU = colony-forming units

The groundwater over use is often perceived as a localized problem, largely confined to

the water deficient regions. Any intensification and development of groundwater resource in

Kathmandu Valley must be given a very careful attention to ensure not to threaten the

sustainability of the resources.


3. Research, development and management:

The high rate of groundwater abstraction coupled with degrading quality of groundwater

from shallow aquifer had put tremendous pressure on deep aquifers with relatively good water

quality, but slow recharge rate. Such condition calls for attention to the scientific as well as

political community to intervene the current management system to rehabilitate or restore

groundwater resources. The lack of systematic and reliable information pertinent to ground water

development, management and research is another potential barrier for appropriate action to take

place. Adequate attentions have not been given to the monitoring mechanisms. Many studies

are focused primarily on groundwater development and fewer researches address issues of

monitoring, management and regulations. In addition, the alternative sources of groundwater

need to be explored and researched.

Management and responses to groundwater related issues are complicated by variations in

resource characteristics and social conditions. Hydro-geologic complexities relate to the changes

in groundwater resource dynamics that exist both between and within aquifer systems.

Natural variation in climatic conditions is also important since precipitation characteristics

greatly influence management options. The ability to capture run-off for recharge of aquifers, for

example, depends not only on the intensity and duration of precipitation events, but also

infiltration capacity of the soils. Social variation may present some challenges to the

development of groundwater management systems (Moench and Burke. 2000), but regulatory

agencies need to pay greater attention for managing this resource.

Lack of data and scientific understanding of groundwater resources is often a critical gap

undermining the development of groundwater management approaches and institutions. The

absence of data often limits the degree to which researchers are able to quantify and describe


aquifer dynamics. Thus, information on their dynamics is generally essential for management.

Equally important, however, are the ways in which raw data and information are treated,

presented and used. Information is only useful if it is used. Information must be accessible to

potential users and presented in a manner the users and researchers can understand. Data

collection is, however, expensive and some judgment as to the required precision always has to

be exercised. For long-term monitoring, broad categories of data include water-level fluctuations,

determination and changes of groundwater flow parameters, water-quality trends and key

pollution indicators. This may be accompanied by regional analysis of the aquifer systems that

will in turn allow targeting of data collection and data types. The management needs that are

identified with long-term monitoring can be the subject of detailed programs to better understand

and characterize local aquifer systems. Basic scientific research is needed to deal with

heterogeneous aquifers, model verification and validation, and relationships between

contaminants and aquifer material. Indirect ways of managing groundwater resources

management would be use of rainwater harvesting techniques to reduce stress on direct use of

groundwater (Dixit and Upadhyaya, 2005). More research in this field in needed.

The researches on the groundwater suggest that water quality may be of bigger concerns that

need immediate interventions. The priorities must be set to manage waste disposal systems and

further pollute existing sources of water. The aquifer system and pumping from the deep aquifer

should be restricted and alternative sources need to be explored and researched until safe

pumping rates for these systems are determined. The system should be studied well. The

integrated effort of mapping, monitoring and modeling is necessary to predict the impacts of

water resource management interventions on key environmental, social and economic services.

Information essential for each of these includes the following:


Hydrogeologic maps identifying aquifers, the characteristics of geologic formations and

major surface-water features need to be developed in greater details.

Location of wells need to be geo-referenced along with their formation characteristics

and water quality variations at depth

Major water-use patterns, key environmental features, cities, agricultural areas and

industries along with potential points of contamination.

Safe pumping rates must be determined.

More reliable water supplies will reduce the need for groundwater pumping, thus

allowing more sustainable use of this valuable water resource.

Climatic parameters, including precipitation, evapotranspiration, cloud cover, solar

radiation, wind speed and humidity data must be collected, evaluated and made

accessible for future researches.

Regular monitoring of groundwater quality parameters must be done.

The primary cause of pathogens contamination in groundwater and surface water systems

are due to unregulated disposal of domestic wastes to the water bodies. Regulators must

focus on developing proper waste management schemes that will help lower Nitrate,

Ammonium, Arsenic and Mercury pollution in addition to pathogen contamination.

Measures must be taken to monitor arsenic contaminations in the Valley water. Lessons

must be learnt from the problems that the neighboring countries are facing with these

contaminants.

Water-planning models capable of integrated analysis of water demand, use and supply

systems need to be evaluated. Hydrologic and ecologic models for detailed analysis of


groundwater flow patterns, specific aquifer conditions and surface stream hydrology and

water resource management will help better understand the groundwater dynamics.

4. Conclusions

Conservation and management of groundwater resources need to focus on the ability of the

resource to produce services such as environmental, societal, and environmental services. Water-

level declines greatly increase the probability of impacts on streams, wetlands and the occurrence

of subsidence, effecting environmental services. As levels decline, drilling and pumping costs

increase. Water may still be physically available, but the cost of extraction can be sufficiently

high affecting these services. Groundwater resources and its use are much more difficult to

monitor. But the ability to monitor resource use is often critical for the effective development

and management of these resources. Public and policy-maker perceptions of groundwater

represent another important problem. Groundwater is often viewed as an inexhaustible resource,

cleaned by the filtering action of aquifers. These perceptions do not reflect reality, and often

result in use patterns that cause unanticipated problems. The focus must therefore be given to

educate general public or users the importance of this valuable resource.

The full impacts of groundwater pollution on environment, society and economy of the

country have never been comprehensively assessed. The growing number of wells, uncontrolled

pumping and unregulated disposal of pollutants are in the Kathmandu Valley all proximate

causes of emerging groundwater problems. Current levels of groundwater abstraction over and

above the natural rates of replenishment are already significant, but aquifer systems exhibit a

variety of responses to stress that require in-depth study. Water quality issues of the Valley are

apparent from the literatures. This calls for more research that will address integrated approach

on availability and quality of groundwater for past, current and future scenarios.


Acknowledgements

The authors would like to thank Dr. Rajith Mukundan, City University of New York, Institute for Sustainable Cities,

and David Lounsbury, GIS Specialist, New York City, Department of Environmental Protection for providing

assistance with this paper.


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