1. General Model Information
Main medium: air+terrestrial
Main subject: biogeochemistry, hydrology, agriculture
Organization level: Ecosystem
Type of model: ordinary differential equations
Main application: research, education, expert system/decision support
Keywords: rainwater harvesting, water conservation, climate generator, infiltration, runoff, soil-water model, crop growth, semi-arid tropics
Mark Damion Bede Young
Department of Agricultural and Environmental Science
King George VI Building
University of Newcastle upon Tyne,
NE1 7RU, UK
Phone: 0191 222 6942
Fax: 0191 222 5228
Damion Young and John Gowing,
The PARCHED-THIRST Model has been developed over a period of four years with the aim of allowing users to quickly and easily simulate the most important processes in a rainwater harvesting system. It can also be applied to a range of other water conservation techniques through manipulation of its parameters. It is a process-based model with three main strengths:
To facilitate its use by those with only limited computer experience, the model is
programmed in Microsoft VisualBASIC which gives it an intuitive and easy to use
- It can add value to experimental work by allowing us to extrapolate experimental results from one site to another and from one season to the next. The traditional approach to the transfer of a successful technology to other areas has been either to introduce the technique 'as is' and see if it works. If it fails (as is often the case) it not only creates suspicion of new technologies in the minds of the recipients, but in the worst cases it can lead to serious problems for the very group it was supposed to be helping. The alternative is to repeatedly test variations of the technology at each target site. While this is less likely to lead to failure, it, like the traditional approach, is wasteful of resources. PARCHED-THIRST can reduce this waste of resources and resistance to uptake by identifying best-bet options before any money, man-power or trust is committed.
- In combination with tools such as Geographical Information Systems
(see Damion Young´s homepage:current work), it can be used to identify target areas with high success and uptake potential, reducing the resources wasted in areas with little promise for the new technology.
- By creating a framework for the study of the system it forces us to identify the
most important processes within a system, adding to our understanding of both the
processes themselves and the interactions with the other processes which make up the system.
- Main Window from where the user controls all aspects of the PARCHED-THIRST
- Run-Time Window which dynamically displays progress with the simulation of a
number of important crop, soil and water variables.
- Climate Generator Main Window which controls and runs all aspects of the
PARCHED-THIRST Climate Generator;
- Climate Generator Summary Window where the user can compare the statistical
properties of observed and generated climate data.
The main sub-models of the PARCHED-THIRST model can be listed as following:
The model is driven by daily rainfall and other agrometeorological data. In order to
provide for simulation of long-term performance, the PARCHED-THIRST Climate Generator
can be used to extend the available historical data. Daily rainfall values are then
converted by the rainfall disaggregator into intensity data which are required by the
infiltration model. The rainfall-runoff process is simulated as an infiltration excess
with infiltration being determined by the Green-Ampt infiltration calculator. Because of
the cost and difficulty of measuring soil hydraulic properties in the field,
pedotransfer functions are included to allow for their prediction from
readily-available soils data. The modified PARCH model adds soil-water redistribution
and crop growth simulation routines which complete the system. RWH is simulated by
having two profiles running simultaneously with runoff from the upper becoming an
input for the lower of the two. Except for climate and soil texture, each profile can
have different characteristics.
- Climate Generator
- Infiltration/Runoff Model
- Soil-Water Model
- Crop Growth Model
(details of sub-models and processes are given in:
PARCHED-THIRST Model homepage)
The PARCHED-THIRST Model has been developed under funding from the UK Department for
International Development (DfID) through research programmes managed by the Natural
Resources International. It is not intended for commercial exploitation and is freely
available in compiled form together with this documentation although we may have to
charge for photocopying and postage costs.
Source of abstract: PARCHED-THIRST Model homepage
II. Technical Information
Programming Language(s): Microsoft VisualBASIC
III. Mathematical Information
Young, M.D.B, Gowing, J.W., Hatibu, N., Payton, R.W., 1998. Assessment and development of pedotransfer functions for sub-Saharan Africa. Submitted to: Physics and Chemistry of the Earth - European Geophysical Society - April 1998.
Gowing, J.W. and Young, M.D.B., 1998. Development of Improved Rainfed Cropping System Incorporating Rainwater Harvesting/Conservation. 2nd Interim Report. University of Newcastle upon Tyne, UK.
Mahoo, H.F., Young, M.D.B., Gowing, J.W., 1998. Rainfall-runoff modelling for semi-arid Tanzania. A comparison of modelling approaches. To be submitted to: Agricultural Water Management.
Gowing, J., Young, M.D.B., Hatibu, N., Wyseure, G.C.L., 1998. Modelling as an aid to technology transfer: assessing the applicability of rainwater harvesting techniques in semi-arid Tanzania. In preparation for: Agricultural Systems special issue.
Mahoo, H.F., Kajiru, G.J., Ngendello, A., Hatibu, N., Rwehumbiza, F.B.R., Mafuru, A., Mzirai, O.B., 1998. Rapid rural appraisal of Maswa district. Sokoine University of Agriculture, Tanzania. 58pp.
Gowing, J.W. and Young, M.D.B., 1997. Development of rainfed cropping system incorporating rainwater harvesting/conservation. 1st Interim Report. University of Newcastle upon Tyne, UK.
Kajiru, G.J., Kileo, R.O, Ngazi, H., 1997. Review of rainwater harvesting for rice production in Maswa district, Tanzania. Ministry of Agriculture, Ukiriguru Agricultural Research Institute. 38pp.
Mahoo, H.F., Rwehumbiza, F.B., Senkondo, E.M., Hatibu, N., Mzirai, O.B., 1997. Proceedings of the workshop to assess farmers' needs in rainwater harvesting and extension workers requirements to meet these needs. 5-7 August 1997, Same, Tanzania. Sokoine University of Agriculture. 28pp.
BACAS, 1997. Exploratory farming systems survey of Western Pare target area. Bureau for Agricultural Consultancy and Advisory Service, Sokoine University of Agriculture. 63pp.
BACAS, 1997. Farming systems survey in Lembeni and Kifaru villages, Mwanga district (Tanzania). Bureau for Agricultural Consultancy and Advisory Service, Sokoine University of Agriculture. 60pp
Gowing, J.W. and Young, M.D.B., 1996. Computer simulation as a tool for technology transfer: interpreting and extending experimental results on rainwater harvesting for maize in semi-arid Tanzania. Conference of Southern & Eastern African Society of Agricultural Engineers, Arusha, October 1996.
Young, M.D.B. & Gowing, J.W., 1996. The PARCHED-THIRST model user guide. University of Newcastle upon Tyne, UK. 109pp.
Young, M.D.B., Gowing, J.W. and Wyseure, G.C.L., 1995. Modelling the response of maize to rainwater harvesting in Tanzania. Proceedings of ODA Plant Sciences Research Programme Conference on Semi-Arid Systems, Manchester, 5-6 September, 1995. p47-48, 66-67.
Hatibu, N., Mahoo, H., Senkondo, E., Simalenga, T., Kayombo, B., Ussiri, D.A.N., 1994. Strategies for Soil-Water Management for Dryland Crop Production in Tanzania. Proceedings of TSAE, Vol 6: 83-97.
Mahoo, H., Gowing, J.W., Hatibu, N., Kayombo, B., Ussiri, D.A.N., Wyseure, G.C.L. and Young, M.D.B., 1994. Rainfall-runoff model for rainwater harvesting design in Tanzania, I: Effects of surface and rainfall characteristics on runoff yield. SADC - Land and Water Management Research Programme. Proceedings of 5th Annual Scientific Conference, Maseru, Lesotho, 10-14 October 1994.
Mahoo, H., Gowing, J.W., Hatibu, N., Kayombo, B., Ussiri, D.A.N., Wyseure, G.C.L. and Young, M.D.B., 1994. Rainfall-runoff model for rainwater harvesting design in Tanzania, II: Comparison and validation of an empirical and a physical model. SADC - Land and Water Management Research Programme. Proceedings of 5th Annual Scientific Conference, Maseru, Lesotho, 10-14 October 1994.
Gowing, J.W., Hatibu, N., Wyseure, G.C.L. and Young, M.D.B., 1994. Local solutions to irrigation needs in semi-arid Africa. The Agricultural Engineer - Journal and Proceedings, 49(4): 20-21. Institution of Agricultural Engineers.
Hatibu, N., Kayombo, B., Mahoo, H., Ellis-Jones, J., Senkondo, E. and Simalenga, T., 1993. Rapid rural appraisal of Mwanga district. June 1993. Sokoine University. 52pp.
Young, M.D.B., Gowing, J.W. and Wyseure, G.C.L., 1993. A physically-based model of rainwater harvesting for Tanzania. Proceedings of 6th International Conference on Rainwater Catchment Systems, Nairobi, Kenya, 1-6 August 1993.
Gowing, J.W., Wyseure, G.C.L. and Young, M.D.B., 1993. A holistic approach as a framework for evaluating rainwater harvesting in semi-arid environments. SADC - Land and Water Management Research Programme. Proceedings of 4th Annual Scientific Conference, Windhoek, Namibia, 11-14 August 1993.
Gowing, J.W., 1992. Evaluation & promotion of rainwater harvesting in semi-arid areas. Project Inception Report, University of Newcastle. 31pp.
V. Further information in the World-Wide-Web
VI. Additional remarks
Last review of this document by: J. Bierwirth Wed Nov 25 17:45:06 MET 1998
Status of the document:
last modified by
Tobias Gabele Wed Aug 21 21:44:47 CEST 2002