Department of Water Resources Studies

Success Stories:

Groundwater Protection

Protection of groundwater quality needs appropriate solutions that take into account the overlap of social, agricultural and economic policies. This requires using advanced methodologies to allow the identification of groundwater vulnerability, especially if it is the main source of natural water as is the case of most of Arab countries.

Drastic method is one of the most competent methods used for determining the groundwater vulnerability as long as the required information usually accessible. The resulted maps are easy to read and interpret by the decision makers. DRASTI index can identify areas that are more susceptible to groundwater pollution as higher values mean more vulnerable areas.

This method has been applied to the uppermost aquifer in the United Arab Emirates. The required layers were drawn according to available data and in collaboration with the Ministry of Environment and Water.

Groundwater vulnerability map of the upper most aquifer in UAE.

Overexploitation of groundwater (mainly from the uppermost aquifer) has led to a great water imbalance because groundwater recharge is hardly enough to cover part of this pumping. This resulted in increasing water deficit that reached more than 1.8 billion cubic meters per year. The demand for groundwater remained on the rise at a rate of 5% per year despite the decline in the contribution of groundwater to meet the needs of domestic and urban needs. This led to depletion of the aquifer and deteriorating of its water quality in addition to emergence of seawater intrusion in the coastal plains. This unfortunately increased the importance of this aquifer and summoned application of advanced methods to determine its susceptibility to contamination.

DRASTIC method has been applied to the uppermost aquifer in the United Arab Emirates. The required layers were drawn according to available data and in collaboration with the Ministry of Environment and Water.

The resulted final map shows DRASTIC index values for the entire UAE region. It shows that the most vulnerable areas are far north where fractured rocks outcropped. The coastal areas are found to be highly vulnerable because of the high values of the aquifer media index. The accuracy and scale of this map is as accurate as the data available, however as the data are divided into layers, it is easy to update and rebuild again.

Figure: DRASTIC index values for UAE

FLOOD MANAGEMENT AND LAND REHABILITATION IN EL QAA WATERSHED, Lebanon

This project was implemented in cooperation of ACSAD, GIZ, and the ministry of agriculture in Lebanon.

El-Qa'a city is subject to annual flash flood which results from heavy and intense rainfall events. Torrent coming from the nearby valleys causes severe damage to houses and properties in the city

The project objective was to mitigate and reduce the impacts of the flash floods on the city of El-Qa'aand the agricultural areas located downstream of the watershed and rehabilitate degraded land by water erosion

Study area

The El-Qa'a watershed is located in the northeast of Bekaa Valley, Lebanon at latitude 34°19'0.70"N and longitude 36°30'37.03"E. The terrain is quite steep

and mountainous inclines to the East. Elevation in the watershed varies from 835 m to 1600 m above mean sea level. The total watershed area is 18.74 km2

Flood in RassBalabak Area

the average slope of the watershed is 26.17 %, the watershed drain directly into El-Qa'a city

watershed boundary and major streams

Daily rainfall data for the El-Qa'a is available between years 1965 and 1969 only. Average yearly rainfall in El-Qa'a city during this period was 208.1 mm which is usually falling in October throw May. Maximum daily rainfall during this period was 35 mm which occurred in 1968.

Total yearly rainfall and maximum daily rainfall between year of 1965 and 1969 for the El-Qa'a city

Average 1969 1968 1967 1966 1965 Year

208.1 162.3 216.1 284.2 169.8 208.0 Total yearly

rainfall

16.0 35.0 23.0 22.0 20.0 Max daily rainfall

Topographic data

Land elevation data for the study area was provided from 1/20.000 Topographic maps of Lebanon published in 1962 Army by the General Directorate of Geographic Affairs of the Lebanese. A DEM derived from this map for the study area.

Soils

The soil map used is the result of the analysis and reclassification of the soil map of Lebanon at the 1/50.000 scale and published in 2006 by the NCRS.

Figure 2 shows the hydrologic groupings of soils in the watershed area according to SCS classification. Soil Type B which has a moderate infiltration rate is the dominated soil type in the watershed

Soil Hydrological group in the studied watershed

Land use

A Land cover – Land use geodatabase of Lebanon 1/20.000 published in 2002 ((LCLU, 2002)) was used to conceptualize the different land cover categories present over the study area. Arid rangeland is the predominant land use in the watershed,

Land use map in the studied watershed

3/sec and 193000 m3peak flow and runoff volume was estimated to be 38.5 m Therespectively based on land use and soil map. The aim of the project was to reduce the peak flow by 50 %.

The hydrograph at the watershed outlet

The following interventions were proposed in the watershed

• Stone Contour Bunds, • Contour Stone Walls, • Gradoni Terraces, • Check Dams • Hafeers • Gabion Diversion Structures and Spillways, These structures were planned to function in several different ways:

• to assist in the establishment of plants • to provide soil and water conservation; • to decrease the velocity of runoff water; and • to provide on-site storage of runoff water) to serve in total the purpose of flood

control

In order to mitigate the flood peak, six locations within the catchment areas have been recognized as potential locations for building Hafeers. In addition to

hydrological factor the following issues were considered: 1) current land use where priority given to the site which are not currently cultivated, 2) Topographical features such as slope and area, 3) willingness of land owner to construct the pond on his/her property

Location of the three proposed Hafeers within the El-Qa'a watershed

The photos below shows some of the intervention constructed in the watershed area

Check dam

Stone Contour Bunds

Hafeers

The project implementation finished in April 2007. During May of the same year Major flood storms occurred in the area. The constructed structures in watershed succeeded to reduce flow significantly and damage due to the flood was confined into the catchment area. The El-Qa'a city did not suffer from any destruction due to the flood.