Characterization of Chyulu Hills Watershed Ecosystem Services in South-Eastern Kenya

John Warui Kiringe,Fiesta Warinwa,Francis Mwaura

doi:10.5539/enrr.v6n3p65

Abstract

Water is an important good provided by watersheds and is critical in sustaining life and socio-economic development. This study evaluated water provision in the Chyulu Hills watershed which is one of the important dry land water catchments in Kenya. Surface water discharge was mainly through rivers and springs with the latter being more prevalent than the former while ground water provision was primarily through boreholes and shallow wells. Springs discharged the highest water volume annually estimated at 128.14million m3 or 85.14% of all the water discharged in the watershed, with shallow wells and boreholes discharging the least water. For all the springs found in the watershed, Mzima springs discharged the highest water volume estimated at nearly 113.15 million m3 annually or 88.30% of the water produced by all the springs; and about 75.19% of the water in the entire watershed. Rivers which were active had a total water discharge of about 20.66million m3 per year, with Kibwezi River discharging 17.59 million m3 annually or 85.14% of all the water from rivers. Shallow wells were mainly prevalent at Nthongoni and the Makindu, and their annual water discharge was about 16.96million m3 per year with boreholes contributing 98.87% (approximately 16.76 million m3/yr.) of the ground water, and the rest (19,169.92m3/yr.) being contributed by shallow wells. The total amount of water discharged in the watershed by the combined water source types was about 150.49 million m3/yr.

Highlights

Ecosystems are ecological entities comprising of an assemblage of diverse fauna and flora and their supporting abiotic attributes including landscape, climate and hydro-geologic systems (MEA, 2005)
The drainage network within the watershed varies from one sector to the other, with the Northern, Eastern and Western zones having a spatial coverage of approximately 4,700Km2, 3965Km2 and 3788Km2 respectively. These sectors were characterized by a high density of streams and rivers of about 2,135 Km2, 2,074Km2 and 827Km2 in the Northern, Eastern and Western zones respectively. This indicates there was a superior drainage density or network on the North-eastern side of the watershed, followed by the South-eastern side which conforms to the high rainfall received in these sectors
Chyulu Hills watershed is important in water provision in a region characterized by low and unreliable rainfall; and springs are critical surface water discharge sites while boreholes and shallow wells are key water provision systems for ground water

Summary

Introduction

Ecosystems are ecological entities comprising of an assemblage of diverse fauna and flora and their supporting abiotic attributes including landscape, climate and hydro-geologic systems (MEA, 2005). Ecosystems generally provide a wide range of goods and services such as; food, clean water, energy, climate regulation, biogeochemical and nutrient cycling, flood disaster mitigation, biodiversity support, spiritual and cultural benefits all which maintains life on earth (Daily et al, 1997; de Groot, Matthew, & Roelof, 2002). These benefits are commonly referred to as ecosystem services (MEA, 2000 & 2005) and are usually grouped into four key categories. An ecosystem does not always offer all the four types of services simultaneously

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