909 - new, coupled marmites-modflow โฆ...department of water resources (wrs) problem statement...
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909 - NEW, COUPLED MARMITES-MODFLOW MODEL IMPROVING SIMULATION OF SUBSURFACE EVAPOTRANSPIRATION
Alain Pascal FrancesITC, University Twente, Enschede, Netherlands
Maciek Waclaw LubczynskiITC, University Twente, Enschede, Netherlands
As subsurface evapotranspiration is poorly simulated in existing hydrological models, a new, coupled model composed of land surface and soil zone MARMITES model and groundwater MODFLOW-NWT model was developed with the aim of incorporating model-based partitioning and sourcing of evapotranspiration (ET), as part of spatio-temporal water balancing at the catchment scale. The partitioning of ET involves its separation into evaporation and transpiration while the sourcing of evaporation and transpiration involves separation of each of the two into soil and saturated zone components.
The MARMITES-MODFLOW coupled model was applied to the La Mata catchment (Salamanca, Spain) to demonstrate its capability to simulate complex hydrological systems. The catchment was characterized by a semi-arid climate with rainfall 500 mm y-1, granitic bedrock, shallow groundwater and sparse oak woodland. The model was calibrated in transient using daily data of two hydrological years. The water balance results of the partitioning and sourcing of ET involved (in % of rainfall): soil evaporation (34.7%), soil transpiration (8.0%), groundwater evaporation (8.5%) and groundwater transpiration (2.0%). Accordingly, the gross recharge was 28.5% and groundwater exfiltration 17.3%, implying low net recharge 0.7%.
The presented MARMITES-MODFLOW model constitutes a powerful tool to analyze catchment water dynamics and water balances in details, accounting separately for impacts of evaporation and transpiration on groundwater resources. The model generates spatio-temporally variable maps of unsaturated and saturated zone fluxes, well-depicting recharge and discharge zones. It can be particularly helpful in analyzing impacts of climate and land cover changes on groundwater resources and for mapping groundwater dependent ecosystems.
The MARMITES-MODFLOW is developed in Python, open-source and freely available at: http://code.google.com/p/marmites/.
Session S8.9 - Aqua 2015 - 42nd
IAH Congress
1
NEW, COUPLED MARMITES-MODFLOW MODEL IMPROVING SIMULATION OF SUBSURFACE EVAPOTRANSPIRATION
A.P. Francรฉs, M.W. Lubczyลski
with contributions of E. Balugani, L.Reyes-Acosta, Ch.v.d.Tol
ITC, University of Twente
Department of Water Resources (WRS)
PROBLEM STATEMENT
Evapotranspiration
partitioning
Sourcing
Net recharge (๐ธ๐ฅ๐๐ = 0)
๐ธ = ๐ผ + ๐ธ๐ ๐ข๐๐ + ๐ธ๐ ๐๐๐ + ๐ธ๐ + ๐ฌ๐
๐ = ๐๐ ๐๐๐ + ๐๐ + ๐ป๐
๐ธ๐ = ๐ธ + ๐
๐ ๐ = ๐ โ (๐ฌ๐ + ๐ป๐)
3/13
MARMITES-MODFLOW COUPLED MODEL
๐ธ๐ partitioning and sourcing
Spatio-temporal water flux assessment
transient and distributed grid-based model
land surface hydrological processes
meteorological forcing, interception, surface storage, runoff and evaporation from open water
soil reservoir / unsaturated zone
hydrological processes
evaporation, transpiration, percolation and soil moisture
driving forces
rainfall, potential evaporation and potential transpiration
parameterization
vegetation, soil, percolation zone and aquifer reservoirs
state variables
hydraulic heads and soil moisture
Python programing language
https://github.com/AlainPascalFrances/marmites
MARMITES-MODFLOW COUPLED MODEL
MARMITES-MODFLOW COUPLING
5/13
EVAPORATION AND TRANSPIRATION PARTITIONING
6/13
Vegetation
๐ = ๐๐ ๐๐๐ + ๐๐ + ๐๐
Vegetation and soil types mapped in each grid cell using remote sensing images
Bare soil ๐ธ = ๐ธ๐ ๐๐๐ + ๐ธ๐ + ๐ธ๐
groundwater evaporation
Exponential decay between
๐ธ๐ ๐๐ธ๐ and the depth of
groundwater table ๐ (Shah et al,
2007).
EVAPORATION AND TRANSPIRATION SOURCING
7/12
groundwater transpiration
Example of simulated drying tree behavior
under water stress (notice, with reduction
of soil moisture, first ๐๐ increases then
decreases with ๐ decline).
8/13
semi-arid catchment (~6 km2)
weathered and fractured granite
shallow water table (~2 m)
limited human influence on
water resources
2 main tree species
>20 years monitoring
LA MATA STUDY CASE
water fluxes maps (average of 2 hydrological years)
= -
net recharge (๐ ๐)
gross recharge (๐ ๐)
๐ธ๐
๐๐
๐ธ๐ฅ๐๐
LA MATA STUDY CASE
10/13
water fluxes maps water fluxes time series
LA MATA STUDY CASE
RAINFALL
EVAPORATION
TRANSPIRATION
11/13
water fluxes maps water fluxes time series
LA MATA STUDY CASE
RAINFALL
RUNOFF
RECHARGE
EXFILTRATION
GW ET
12/13
water fluxes maps
water fluxes time series
water balance at the catchment
scale (Sankey diagrams)
LA MATA STUDY CASE
VEGETATION
SURFACE
SOIL
PERCOLATION
GROUNDWATER
Validation - poster ID 939 (S.5.8)
MARMITES-MODFLOW:
is an open-source code https://github.com/AlainPascalFrances/marmites
partitioning and sourcing of subsurface evapotranspiration
code with spatio-temporally water balance validated with field
independent methods (eddy covariance system, sap flow
measurements, stable isotopes, evaporation modelling);
Introducing processes of partitioning and sourcing of ET into modelling
protocol, makes ET simulation more realistic than ever before; more
realistic models such as M-M, will improve water management but also can
contribute to environmental sciences
Development of Earth Observation Methods can stimulate and fully
automatize the use of satellite remote sensing data as input for integrated
hydrological models
CONCLUSIONS
14/13