Agricultural Water Management 152 (2015) 286–298 Contents lists available at ScienceDirect Agricultural Water Management jou rn al hom epage: www.elsevier.com/locat e/agwat Contributions of lateral flow and groundwater to the spatio-temporal variation of irrigated rice yields and water productivity in a West-African inland valley Petra Schmitter a,b,c,∗ , Sander J. Zwart a , Alexandre Danvi d , Félix Gbaguidi e a Africa Rice Center, Cotonou, Benin b Department of Civil & Environmental Engineering, National University of Singapore, Singapore c International Water Management Institute, East Africa & Nile Basin Office, Addis, Ethiopia d Department of Geography, University of Bonn, Bonn, Germany e Inland Valley Unit, Directorate of Rural Engineering, Ministry of Agriculture, Livestock and Fisheries, Porto Novo, Benin a r t i c l e i n f o Article history: Received 27 June 2014 Accepted 15 January 2015 Available online 25 February 2015 Keywords: Groundwater Irrigation Rice Water management Water productivity West-Africa a b s t r a c t Water management techniques to elevate rice yields and productive use of water resources in Africa, frequently lack a substantial spatial assessment as they are often based on plot level measurements without taking into account toposequential effects present in the landscape. These effects have been shown to significantly affect spatio-temporal variations in water availability and rice productivity in Asia. Therefore, this study addresses the spatio-temporal variations of the various water components within irrigated toposequences in an African inland valley and assesses its effect on water productivity and respective rice yields for two irrigation practices: (i) continuous flooding (CF), a well-known water management practice in rice cultivation used worldwide and (ii) a reduced irrigation scheme (RI) where irrigation is applied every 5 days resulting in a 1–2 cm water layer after irrigation. The lateral flow observed in the inland valley had a strong two-dimensional character, contributing to water gains between fields, located at the same toposequential level as well as along toposequences. The toposequential effect on sub-surface hydrological processes masked the overall effect of water manage- ment treatment on rice production. Additionally, the associated water productivity (WP) was not found to differ significantly between the treatments when standard calculations (i.e. net irrigation and evapotrans- piration) were used but a clear toposequential effect was found for the fertilized lower lying fields when the net irrigation was corrected by the lateral flow component. Results of the established mixed regres- sion model indicated that based on the groundwater table, rainfall and standard soil physico-chemical characteristics rice yields can be predicted in these African inland valleys under continuous flooding and reduced irrigation practices. Validation of the established regression function of inland valleys, repre- senting various groundwater tables in the region, could lead to improved regression functions suitable to estimate spatial variation in rice production and water consumption across scales as affected by water management, fertilizer application and groundwater tables. © 2015 Elsevier B.V. All rights reserved. 1. Introduction African countries depend on 40% of international food mar- kets and rice imports, mostly from Southeast Asia, to fulfill their demands (Tsujimoto et al., 2013). In 2011, 11 million tons of rice was produced in West Africa and an additional 6.3 million ∗ Corresponding author. International Water Management Institute, East Africa & Nile Basin Office, Addis, Ethiopia, Phone: +251 (0) 11 6172207, Fax: +251 (0) 11 6676923 E-mail address: p.schmitter@cgiar.org (P. Schmitter). was imported to meet its growing rice demand (FAO Stat, 2011). This dependency on food markets makes West-African countries vulnerable to price shocks such as those witnessed in 2008 (Seck et al., 2013), which can lead to political instability and social unrest. Most West-African countries have developed National Rice Sector Development Strategies outlining the pathways for self-sufficiency by the year 2018. The development of new irrigated rice systems in lowland environments and intensification of lowland rice produc- tivity through rehabilitation of irrigation infrastructure are often prioritized by national governments to increase national rice pro- duction. Since the food crisis in 2008, a strong growth in rice http://dx.doi.org/10.1016/j.agwat.2015.01.014 0378-3774/© 2015 Elsevier B.V. All rights reserved.