Sustainable conjunctive water management in irrigated agriculture: Model formulation and application to the Yaqui Valley, Mexico

Abstract

[1] This paper investigates strategies to alleviate the effects of droughts on the profitability and sustainability of irrigated agriculture. These strategies include conjunctive management of surface water and groundwater resources, and engineered improvements such as lining of irrigation canals and addition of regional pumping well capacity. A spatially distributed simulation-optimization model was developed for an irrigated system consisting of multiple surface water reservoirs and an alluvial aquifer. The simulation model consists of an agronomic component and simulators describing the hydrologic system. The physical models account for storage and flow through the reservoirs, routing through the irrigation canals, and regional groundwater flow. The agronomic model describes crop productivity as a function of irrigation quantity and salinity, and determines agricultural profit. A profit maximization problem was formulated and solved using large-scale constrained gradient-based optimization. The model was applied to a real-world conjunctive surface water/groundwater management problem in the Yaqui Valley, an irrigated agricultural region in Sonora, Mexico. The model reproduces recorded reductions in agricultural production during a historical drought. These reductions were caused by a decline in surface water availability and limited installed pumping capacity. Results indicate that the impact of the historical 8-year drought could have been significantly reduced without affecting profit in wet years by better managing surface water and groundwater resources. Namely, groundwater could have been more heavily relied upon and surface water allocation capped at a sustainable level as an operating rule. Lining the irrigation canals would have resulted in water savings of 30% of historical reservoir releases during wet years, which could have been used in subsequent drier years to increase agricultural production. The benefits of a greater reliance on groundwater pumping by installing additional wells are limited due to pumping restrictions near the coast to avoid seawater intrusion and due to increased pumping costs.

Linking knowledge with action in the pursuit of sustainable water-resources management

“…In Ceará there are management roles at the state and federal level as well as local water committees, and in the Ping River Basin a hierarchy of river basin and subbasin committees is overseen by a National Water Resources Committee. Water use in the Yaqui Valley is nearly exclusively agricultural: With its legacy as the birthplace of the irrigated-wheat Green Revolution, the Yaqui Valley has contributed up to 40% of Mexico's total wheat output in recent years (15). Irrigation water from the Yaqui River is the lifeblood of the regional economy; the main focus of water management is on supply-side solutions, especially infrastructure improvements and intensified groundwater-pumping schemes to augment surfacewater supplies.…”

Impact of Sowing Date on Yield and Water Use Efficiency of Wheat Analyzed through Spatial Modeling and FORMOSAT-2 Images

“…Indeed, a severe drought was observed from 1994 to 2002 in northern Mexico [12,13], which resulted in an emptying of the reservoirs. The 19 dams located on the rivers of the Gulf of California contained less than 20% of their storage capacity in 1999 [12], and by May 2000, the main reservoir levels had slipped under "dead storage", i.e., the point at which the remaining water was accessible only by pumping [11,14,15]. This climatic crisis resulted in an increase of groundwater use and in a reduction of the crop production: sown areas have recovered less than 25% of the whole Yaqui Valley during the 2003 to 2004 agricultural season [14,16].…”

Reliable conjunctive use rules for sustainable irrigated agriculture and reservoir spill control

“…Groundwater provides additional insurance against reductions in agricultural production during droughts [Bredehoeft and Young, 1983;Tsur, 1990]. A drawback is that increased groundwater pumping during extended droughts may lead to severe aquifer head drawdowns, resulting in high pumping costs and seawater intrusion in coastal aquifers [Willis and Finney, 1988;Reichard and Johnson, 2005;Schoups et al, 2006]. When developing conjunctive water management strategies, all these issues should be taken into account.…”

“…[6] We build on a deterministic spatially distributed numerical simulation-optimization model for the Yaqui Valley developed by Schoups et al [2006], and present here for the first time an approach that involves a combination of methods enabling us to consider a more complex, multiannual, regional water management problem under uncertainty. Methodologically, Schoups et al [2006] studied elements of water management with a deterministic model of the hydrologic systems (surface water reservoirs and alluvial coastal aquifer), and a model that simulates crop production.…”