Development of the Indus River System Model to Evaluate Reservoir Sedimentation Impacts on Water Security in Pakistan

Geoffrey M. Podger,Mobin-ud-Din Ahmad,Joel P. Stewart,Yingying Yu,Syed Muhammad Mehar Ali Shah,Zarif Iqbal Khero

doi:10.3390/w13070895

Geoffrey M. Podger, Mobin-ud-Din Ahmad + Show 4 more

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https://doi.org/10.3390/w13070895

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Abstract

Pakistan’s society and economy are highly dependent on the surface and groundwater resources of the Indus River basin. This paper describes the development and implementation of a daily Indus River System Model (IRSM) for the Pakistan Indus Basin Irrigation System (IBIS) to examine the potential impact of reservoir sedimentation on provincial water security. The model considers both the physical and management characteristics of the system. The model’s performance in replicating provincial allocation ratios is within 0.1% on average and the modeling of water flow at barrages and delivered to irrigation canal commands is in agreement with recorded data (major barrage NSE 0.7). The average maximum volumetric error for the Tarbela and Mangla reservoirs are respectively 5.2% and 8.8% of mean annual inflow. The model showed that a 2.3 km3 reduction in storage volume since 1990 equates to approximately 1.3 km3 i.e., a 4–5% reduction in irrigation deliveries, respectively, for Punjab and Sindh in the dry (Rabi) season. This decline indicates that without further augmentation of system storage, the Rabi season supplies will continue to be further impacted in the future. This paper demonstrates the suitability of IRSM for exploring long term planning and operational rules and the associated impacts on water, food and energy security in Pakistan.

Highlights

Pakistan is facing severe challenges related to water, food and economic security
The river system model discussed in this paper aims to address this capability gap by capturing the undocumented operational rules and expert knowledge, through intensive consultations with key federal and provincial stakeholders, in the estimation of seasonal water allocation and the distribution of water resources to canal commands
Many studies may look at potential changes to inflows to the Indus Basin Irrigation System (IBIS) from climate change or potential upstream development, which are uncertain, this study has focused on a historic decrease in available storage through sedimentation, which has shown remarkably consistent trends that will continue

Summary

Introduction

Pakistan is facing severe challenges related to water, food and economic security. It relies utterly on the water of the River Indus and the associated groundwater systems. It operates the world’s largest continuous irrigation system, the Indus Basin Irrigation System (IBIS), which supports food production, energy generation, as well as stock, domestic and industrial supply for the nation [1]. Water security issues in the basin include changing resource availability [4,5,6,7,8,9,10,11,12,13], growth in demand from competing users [14,15,16,17,18] and the loss of storage capacity through sedimentation [4,19].

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