Ensuring water security of Arial khan river catchment using integrated water resources management model

Abstract

Water security has become an increasingly important issue both at the national and international levels. Bangladesh having an abundance of water during monsoon while the shortage of water during the dry season is far from being water secured. Though water security has been discussed discretely at a different level but a holistic effort to ensure water security is yet to be made. The elements of water security such as sectoral demands of water, conflicting requirements amongst the sectors, balancing between demand and supply including the quality of water can best be understood and managed in a catchment as it is the standard functioning unit. The Arial Khan River catchment consists of parts of Faridpur, Madaripur, Shariatpur and Madaripur districts have all the components of water demands such as agriculture, domestic, commercial, industrial, forestry, fisheries, navigation or recreation and e-flow requirements. The population of the area, sustenance of their livelihood, wellbeing and socio-economic development are intrinsically related to these components of water demand. The catchment is comprised of both urban and rural areas, has the potential of using surface and groundwater which is again being polluted by anthropogenic activities. Huge ongoing infrastructure development will bring changes to the socio-economic development of the area. Though there were studies on water balance but there was no study carried out in Bangladesh on a catchment to ensure water security. In this study an attempt has been made for the Arial Khan River catchment to ensure water security by satisfying all the demands from the available resources including their quality and is projected up to the year 2060.

Based on secondary and primary data, water demands of various sectors have been determined. CROPWAT 8.0 has been used to determine the Agricultural Water Demand while HEC-RAS has been used to verify the water level of Arial Khan River. Water Evaluation And Planning System (WEAP) based decision support tool as part of Integrated Water Resources Management (IWRM) has been utilized for ensuring the water security of the Arial Khan River catchment.

According to the estimation on real time data from 2007 to 2016, it is found that there is considerable amount of unmet demand in Faridpur and Barishal districts. Madaripur district is having enough available resources to meet the demand of all the sectors except for the month of November and December, 2014. Demands of Shariatpur can mostly be met from the available resources except December, January and March. The e-flow requirement can’t be met from the existing flow during the dry season. Navigational and Recreational Water Demand (NRWD) will govern over the e-flow requirement for which flow augmentation to maintain the water level of 1.52m for the Arial Khan River will be required. Water quality for both ground and surface water are deteriorating and need to be treated for domestic uses. The monthly unmet demands for the years 2020, 2030, 2040, 2050 and 2060 were simulated through the use of WEAP. Demands remain mostly unmet in Fardipur and Barishal district. There will not be any unmet demand in Madaripur district while demands of Shariatpur district is almost met with some exception. Increased irrigation efficiency, reuse of grey water, demand side management, further exploitation of groundwater with some policy issues will reduce the unmet demand but will not completely fulfill the requirements to ensure water security of the Arial Khan River catchment.