Abstract:
Abstract Many watersheds experience scarcity of water
for agricultural and domestic use for most part of the year.
Ur river watershed in Tikamgarh district of Madhya Pradesh,
India, falls under a drought prone region of India.
Water allocation and management are essential for sustainable
agriculture for this region. Water Evaluation and
Planning system (WEAP)-based decision support system
can prove to be an effective tool for water allocation,
supply and demand analysis. In the present study, spatially
distributed model by using WEAP-MABIA method has
been developed for analysis and simulation of agricultural
water demands in the Ur river watershed. WEAP-MABIA
method uses dual crop coefficient approach which helps in
computing the separate soil evaporation and transpiration
under various water availability situations. Year
2012–2013 is used as base year for customizing WEAP
model for 8 subwatersheds. The model was calibrated
using PEST tool, available in WEAP. The calibrated model
was used for estimating future water demands and unmet
demands by using future climate series, from 2015 to 2030,
of IPCC scenario- RCP 4.5 of GDFL-ESM2M model. As
per GFDLESM2M model (RCP4.5) predictions, rainfall is
going to greatly vary in the coming years. The years
2020–2021 and 2028–2029 may experience very dry climatic
conditions with 500 mm or less annual rainfall, while
2017–2018, 2023–2024 and 2025–2026 may experience
heavy showers (1200 mm). Straight effects of this rainfall
pattern could be seen in future water availability for agriculture
and resultant crop yield. A high unmet demand
exists in the case of agriculture since the first priority for
water supply is meant to be for domestic purpose. Area
under agriculture in Ur river watershed is large, while
respective water supply is low. This gap puts an extra
pressure on water resources leading to over extraction of
groundwater and related problems. Looking at this scenario,
water allocation requires great attention to narrow
down the gap between existing demands and water supply.
Since area under agriculture is large, water-efficient crops
should be more emphasized. Also, efficient agricultural
practices and rain water harvesting should be promoted in
the study area. Since the watershed falls in semiarid condition
and river flows are seasonal, different stress/deficit
irrigation scenarios can be built using customized WEAP
model to get higher yield.
