Green Water Credit: Cost Benefit Analysis of Soil and Water Conservation Practices in the Upper Tana Catchment

Off Site Cost Benefit Analysis

Esther Njuguna, Davies Onduru, Fred Muchena

Introduction

The small-scale land users in the Tana catchment’s basin are the potential suppliers of water.

There are big waters users down stream of the Tana

basin who are potential private funders of green water credits

Kenya Electricity Generating Company (KenGen) Irrigators (Kakuzi, Delmonte and Yatta canal farmers) Nairobi City Water and Sewerage Company

Objective

In consultation with the main water users, the objectives of the off site cost benefit study were to:

Conduct an off site economic evaluation of hydrological benefits of green water measures as identified in various Green Water Credits reports

Estimate the avoidable costs that green water management could save the government of Kenya in disastrous dry and wet years (Elnino and Elnina effects) in terms of flooding reduction, reduction of productivity losses, enhancing food security, scope for carbon credits etc.

Methodology

Literature review and development of data collection tools

Discussions with large water users Data collection Data entry and analysis; and Report preparation.

Data collection

Water user Interviews with water user representative

Data received by research team

Yatta (WACO and Min of Water)

Yes Yes

KenGen Yes In progress

Delmonte Yes In progress

Kakuzi Yes *

Nairobi Water Yes Yes, gaps being filled

Yatta case study

Yatta district is in the Eastern Province of Kenya

Irrigation potential in Yatta district is estimated at 4,448 hectares but only 1,028 hectares have been exploited (water shortage), supporting approximately 993 households

The Yatta Water and Sewerage Company (Yatta-WASCO) draws water from the Yatta furrow

Water flow in the Yatta canal

The Yatta furrow is 60km long

During a flooding year or during a normal rainy season, the Yatta furrow has water flowing through the 60 km of its length

During a drought year, only about 26-28km of the canal has water flowing

Length of the Yatta canal with water during the year in a normal, flooding and drought year

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Kilometers (normal year) Kilometers (heavy rain year) Kilometers (drought year)

Impact of GWC on the Yatta canal GWC 4 “Increase ground water recharge from

cropland by 4-57% (16-160mm per year) a potential annual gain of accessible water of 160-1600m3 per ha”

higher flows into the water bodies that feed into the Yatta canal extending water availability to the 60km mark and for longer periods of the year; flow rate higher than 1.1m3 per sec

Assumptions for CBA

The total number of hectares under irrigation in the area The number of domestic consumers (317 to 717) and

irrigators (600 to 1000) that would be served by Yatta WASCO

The savings Yatta WASCO would make from avoided tankering costs for emergency water supply to institutions (e.g. the hospital) and other consumers

The savings Yatta WASCO would make from de-silting activities of the Yatta canal.

Higher levies based on water abstracted from the Yatta Canal

Benefits of the GWC to the Yatta community A: Total revenue gains to Yatta community 36,846,424.69 - Reduction in costs by Yatta WASCO of emergency water supply

to institutions during drought

- Revenue to Yatta WASCO from higher numbers of irrigators

- Revenue to Yatta WASCO from higher numbers of water users provided with piped water

- Higher benefits to Yatta small scale irrigators from farms under irrigation (based on gross margins for sukuma wiki; could be higher if high value vegetables are irrigated and marketed)

Benefits of the GWC to the Yatta community B: Total costs increase for the Yatta community

11,854,993.00 Change in costs of water treatment (assumed to increase

to level of flooding)

Change in levies to WRMA

Change in levies to Tana and Athi/WESREB

Change in costs of de-silting the canal

Costs Benefits Results for YATTANet benefits (a-b) Ksh. 24,991,432

Benefit cost ratio 3.11

Net benefits discounted at 10%

Ksh 190,084,829

Net benefits discounted at 12%

Ksh 170,214,142

Net benefits discounted at 14%

Ksh 153,504,871

GWC has a potential to benefit the Yatta community if successfully implemented

Thank you….