Challenges of Water for Food, People and Environment–ICID’s1 Initiative on ‘Country Policy Support Programme’ (CPSP) - Water and Agriculture: Sustainability, Markets and Policies - page 145

Sabarmati River Basin
Sabarmati River Basin (Annex Map - 2) is one of the 24 river basins of India. This
water deficit basin lies on the west coast of India between latitudes 22 ° N to 25 ° N and
longitudes 71 ° E to 73 ° 30' E, and is spread across the States of Rajasthan and Gujarat.
The river outfalls into the Arabian Sea (more specifically in the Gulf of Cambay, or
Khambhat as it is well known locally). The basin has a total drainage area of 21,565 km 2 .
The basin has a tropical monsoon climate. The average annual temperature varies
between 25 and 27 ° C. The rainfall occurs almost entirely during the monsoon months.
The average rainfall of the entire basin is 749 mm. The rate of evaporation is maximum
during April to June due to the rise in temperature and increase in wind speed. The
average annual evaporation losses in the basin are in the order of 1500-2000 mm.
The total population in the basin (2001) is 11.75 million, of which 5.99 million is
urban and 5.76 million is rural. The projected population of the basin for the year 2025 is
19.86 million, of which 10.81 million is urban and 9.05 million is rural.
The annual mean water resource in the basin is estimated as 3,810 million m 3 . Water
consumption of surface water for irrigation has been estimated to be 3,465 million m 3 per
year, including the Mahi command within the Sabarmati basin (1,663 million m 3 ). The
groundwater contribution to agricultural use is estimated as 2,279 million m 3 . The total
demand for the year 2001 was in the order of 5,744 million m 3 . The irrigation demands,
considering the future expansion of areas and development of additional possible irrigable
areas (with infrastructure like main canals ready), is about 4,554 million m 3 . These are
considered in some scenarios studied, which take into account inter-basin water transfer
which has already been in place with an increasing provision in future. These include
imports from the Mahi and Narmada rivers, which adjoin the study basin in its southern
part. Since the basin suffers from overexploitation of groundwater, the groundwater
demand for irrigation in the study has been restricted to the present use of
2,279 million m 3 . Water requirements for humans and livestock in 2001 were
510 million m 3 , which will increase by 2025 to 898 million m 3 . The water requirement for
the existing 20 industrial estates in the basin is 99.64 million m 3 , and the demand is likely
to be 245 million m 3 in 2025.
Basin-wide Holistic Integrated Water Management (BHIWA) Model
Figure 1 shows the schematic of the BHIWA model. The model covers the entire land
phase of the hydrologic cycle, right from precipitation, and various water uses, river flow,
groundwater recharge, returns, and outflow to the sea. The BHIWA model approach asks
for a division of the entire river basin into sub basins and several homogeneous land
parcels; depicting different land use categories such as forest land, pasture, waste land,
wet land, land under infrastructure, land under reservoirs, rain-fed agricultural land,
irrigated agricultural land, etc. is also necessary. The agricultural land can further be
subdivided into parcels to represent broad seasonal cropping patterns (such as perennial
crops, land with a single crop in two four-monthly seasons and not cropped in the third
season, land under two different crops in two seasons and fallow in the third season, and
land that is cropped only in one season and remains fallow in two seasons, etc.). The main
inputs to the model include hydrological data, crop parameters, land use and land parcel
areas, soil moisture capacity for each type of land parcel, irrigation system efficiencies,
coefficients for return flow accounts, changes in reservoir storages, etc.