Catchment water balance

Catchment water balance

1.Host Institution: Jomo Kenyatta University of Agriculture and Technology (JKUAT), P.O. Box 62 000 – 00200 Nairobi, Kenya

2. Supervisors:

(1) John M. Gathenya, PhD (, Professor, Hydrology, Climate Services, Environmental Services, Jomo Kenyatta University of Agriculture & Technology, School of Biosystems and Environmental Engineering

(2) Roger Stern (, Professor of Applied Statistics (Emeritus), University of Reading, UK

3. Project Description:

The long-term water balance equation for a catchment is P = Q + AET + GW + DS, with all terms expressed in mm/year, where P is Precipitation, Q is Runoff, AET is actual evapotranspiration, GW is exchange with groundwater aquifer and DS is change in soil storage. The last two terms are usually small and could be ignored in long term analysis of 5 to 10 years. Hydrologists have been testing different methods to estimate AET. One of the useful approaches now is the Budyko formula. The formula is explained well in the following papers:

Zhang, L., Dawes, W. R. & Walker, G. R., 2001. Response of mean annual evapotranspiration to vegetation changes at catchment scale. Water Resources Research, Vol. 37(No. 3), pp. 701-708.

Teuling, A. J. et al., 2019. Climate change, reforestation/afforestation, and urbanization impacts on evapotranspiration and streamflow in Europe, s.l.: Hydrol. Earth Syst. Sci., 23, 3631–3652, 2019.

With the widely available global datasets of PET (or climate data to calculate PET) and precipitation, the Budyko model can now be used to estimate AET and Water Yield for any desired location. The single parameter of Budyko model is linked to catchment and vegetation properties. It can be estimated from vegetation cover or NDVI (and we do have online datasets for NDVI). We need local discharge data to calibrate this one parameter. Understanding the long-term water balance allows one to establish if discharge time series obtained from the Water Resources Authority is reliable or not.

4. Expected outcomes:

Many countries combine their climatic and hydrological services.  The aims of this internship project is to develop and exploit resources for the processing of hydrological data that parallel those for climatic variables. These combine the development of standard methods of analysis for streamflow data with the use of complex simulation models.

Applications for this internship should be submitted via the online application system, stating clearly the title of the internship.

Deadline for applications: February 28th, 2021 at 11:59 PM Central Africa Time (CAT)

Any inquiries about these internships should be sent to: