High-Resolution, Integrated Hydrological Modeling of Climate Change Impacts on a Semi-Arid Urban Watershed in Niamey, Niger

Boubacar Abdou Boko,Hyoun-Tae Hwang,Edward A Sudicky,Moussa Konaté,Steven J Berg,Nicaise Yalo,Keith Schimmel,Andre R Erler,Pibgnina Bazié,Albachir Seydou Niandou,Ousmane Seidou

doi:10.3390/w12020364

Abstract

This study evaluates the impact of climate change on water resources in a large, semi-arid urban watershed located in the Niamey Republic of Niger, West Africa. The watershed was modeled using the fully integrated surface–subsurface HydroGeoSphere model at a high spatial resolution. Historical (1980–2005) and projected (2020–2050) climate scenarios, derived from the outputs of three regional climate models (RCMs) under the regional climate projection (RCP) 4.5 scenario, were statistically downscaled using the multiscale quantile mapping bias correction method. Results show that the bias correction method is optimum at daily and monthly scales, and increased RCM resolution does not improve the performance of the model. The three RCMs predicted increases of up to 1.6% in annual rainfall and of 1.58 °C for mean annual temperatures between the historical and projected periods. The durations of the minimum environmental flow (MEF) conditions, required to supply drinking and agricultural water, were found to be sensitive to changes in runoff resulting from climate change. MEF occurrences and durations are likely to be greater from 2020–2030, and then they will be reduced for the 2030–2050 statistical periods. All three RCMs consistently project a rise in groundwater table of more than 10 m in topographically high zones, where the groundwater table is deep, and an increase of 2 m in the shallow groundwater table.

Highlights

The Niger River is the primary surface water used for agriculture and the drinking water supply for Niamey, Niger, West Africa
The study area is a 1900 km2 sub-watershed of the middle Niger River basin (Figure 1a) and is located southwest of the Republic of Niger
The observed historical (1980–2005) rainfall and temperature data at Niamey airport station (Figure 2) are compared at different timescales in Figure 3, with the basin-weighted, average, uncorrected historical precipitation simulated by the three regional climate models (RCMs) models

Summary

Introduction

The Niger River is the primary surface water used for agriculture and the drinking water supply for Niamey, Niger, West Africa (located in the middle Niger River basin; see Figure 1a,b). Water 2020, 12, 364 the water distribution network does not cover the entire populated area, and because of recurrent droughts, the Niger River cannot fulfill the total water demand for the area. Groundwater is pumped through open wells and boreholes to provide water to more than 35% [1] of the city’s population of Water 2020, 12,[2]. (b) Local context of the area with Figure 1 Groundwater is pumped through open wells and boreholes to provide water to more than 35% [1] of the city’s population of Water 2020, 12,[2]. 1.3 million b

Objectives

Methods

Results

Conclusion