This paper uses simple hydro-economic optimization to investigate a wide range of regional water system management options for northern Baja California, Mexico. Hydro-economic optimization models, even with parsimonious model formulations, enable investigation of promising water management portfolios for supplying water to agricultural, environmental and urban users. CALVIN, a generalized hydro-economic model, is used in a case study of Baja California. This drought-prone region faces significant challenges to supply water to agriculture and its fast growing border cities. Water management portfolios include water markets, wastewater reuse, seawater desalination and infrastructure expansions. Water markets provide the flexibility to meet future urban demands; however conveyance capacity limits their use. Wastewater reuse and conveyance expansions are economically promising. At current costs desalination is currently uneconomical for Baja California compared to other alternatives. Even simple hydro-economic models suggest ways to increase efficiency of water management in water scarce areas, and provide an economic basis for evaluating long-term water management solutions

Irrigated agriculture is the largest water user in many regions, and agricultural water use efficiency and consumption has been studied by several authors. This paper provides a framework and application of economic valuation of water for agriculture in three regions in northern Baja California, Mexico, namely Guadalupe, Maneadero and Mexicali Valleys. Positive mathematical programming (PMP), a deductive valuation technique, was the framework used for this estimation using water delivery data reported by the National Water Commission in Mexicali, production costs and cultivated area, production factors use from the Agriculture Ministry (SAGARPA); and other data from previous studies. Analysis of the results shows that marginal economic water value in Mexicali is at least 2.6 times the water price paid by farmers. Guadalupe and Maneadero with higher value agriculture, have higher marginal economic values of water than Mexicali, albeit closer to their water costs. Small shortages increase this economic value for farmers. Estimated price elasticities of irrigation water for each turn-out are inelastic for all regions and within the range of most previous studies. Policies aimed to reduce water consumption by decreasing current pumping subsidies are encouraged.

Based on a total of 135 stable isotope analysis (δ18O, δD) carried out on surface and groundwater samples, as well as on rainwater samples between 2004 and 2011 in 5 different regions in Baja California, an isotopic evaluation of the region was established. The results showed a depletion gradient of -0.25 ‰ δ18O per 100 m rise in elevation throughout the study area. Considering an unaltered δ18O signature for the thermal springs, the recharge areas of these waters are at elevations over 1400 m outside of the present watersheds, indicating the presence of regional flow systems next to the local flow regime feeding the cold springs and wells. The Mesa de Andrade area has a completely different signature with values of -105 for δ18O and -13 for δD.

Around the world, groundwater constitutes approximately 94% of the total volume of freshwater, providing a wide range of economic and environmental services. In Baja California, Mexico, groundwater provides around 60% of the required demand and has become an essential source for agriculture, industry and domestic use. Particularly, in the Guadalupe Valley, in the municipality of Ensenada, the development of diverse activities depends on the water stored in the aquifer. Among these activities, agroindustry stands out; due to its high value, it represents a regional development factor. The objective of this research consisted of identifying potential aquifer recharge sites as tools for the planning process for regional socio-economic development. The study consisted of four fundamental parts: (1) Compilation and identification of entry data of the recharge model; (2) identification and evaluation of the sites that have a greater or lesser capacity of water recharge, using a geographic information system (GIS); (3) comparison of the model results with the piezometric data of two wells in the study area and their relationship with precipitation events; (4) finally, the development planning instruments of the study area were identified, and the relevance of the present study as a planning tool was evaluated. The results obtained showed that 16.31% and 3.64% of the area presents a high and very high recharge potential, respectively. This article is useful for the authorities and users to develop projects for aquifer recharge in the Guadalupe Valley.

A two-dimensional algorithm for underground water flow simulation was modified and adapted to the geohydrologic conditions of the Guadalupe valley located in the state of Baja California in northern México. In order to solve the numerical model using the balance equation, the central finite differences with spatial and temporal constant increments method were used. Such model considers a heterogeneous and transient unconfined aquifer. Modeling and calibration processes are presented using the data of water table levels provided by the water level data loggers installed in a monitoring network and precipitation data from climatic stations of both seasons: 2009-2010 and 2010-2011. It was possible to locate, correlate and model specific rainfall-recharge events with the aim of obtaining an estimation of how these events are directly reflected on the water table level of the aquifer and how it reacts against simulated extraordinary events.

The amount of groundwater recharge by channel infiltration is estimated for El Barbon basin, in Baja California, Mexico. The basin’s lower portion includes the valleys of Ojos Negros and Real del Castillo Viejo, which are crossed by several ephemeral washes, including the mainstem El Barbon Wash. A distributed catchment model with the capability for nonlinear channel routing and channel abstraction is used to calculate groundwater recharge by channel infiltration for storm events of 2-, 5-, 10-, 25-, 50-, and 100-yr return period. The results confirm that event channel infiltration can be a substantial component of the vertical recharge. q 1999 Elsevier Science B.V. All rights reserved.

The amount of groundwater recharge by channel infiltration is estimated for El Barbon basin, in Baja California, Mexico. The basin’s lower portion includes the valleys of Ojos Negros and Real del Castillo Viejo, which are crossed by several ephemeral washes, including the mainstem El Barbon Wash. A distributed catchment model with the capability for nonlinear channel routing and channel abstraction is used to calculate groundwater recharge by channel infiltration for storm events of 2-, 5-, 10-, 25-, 50-, and 100-yr return period. The results confirm that event channel infiltration can be a substantial component of the vertical recharge. q 1999 Elsevier Science B.V. All rights reserved.

The Guadalupe Valley aquifer is the only water source for one of the most important wine industries in Mexico, and also the main public water supply for the nearby city of Ensenada. This groundwater is monitored for major ion, N-NO3, P-PO4, Fe, As, Se, Mo, Cd, Cu, Pb, Zn and Sb concentrations, as well as TDS, pH, dissolved oxygen and temperature. High concentrations of N-NO3 (26 mg l)1 ), Se (70 lg l)1 ), Mo (18 lg l)1 ) and Cu (4.3 lg l)1 ) suggest that groundwater is being polluted by the use of fertilizers only in the western section of the aquifer, known as El Porvenir graben. Unlike the sites located near the main recharge area to the East of the aquifer, the water in El Porvenir graben has low tritium concentrations (<1.9 TU), indicating a premodern age, and thus longer water residence time. No significant variations in water quality (generally <10%) were detected throughout 2001–2002 in the aquifer, suggesting that reduced rainfall and recharge during this dry period did not significantly affect water quality. However, the wells nearest to the main recharge area in the Eastern aquifer show a slight but constant increase in TDS with time, probably as a result of the high (200 L S)1 ) uninterrupted extraction of water at this specific recharge site. Relatively high As concentrations for the aquifer (10.5 lg l)1 ) are only found near the northern limit of the basin associated with a geological fault.

A regional groundwater flow model was developed, in order to evaluate the water table behavior in the region of the Guadalupe Valley, in Baja California, Mexico. The State of Baja California has been subject to an increment of the agricultural, urban and industrials activities, implicating a growing water-demand. However, the State is characterized by its semi-arid climate with low surface water availability; resulting in an extensive use of groundwater in local aquifer. Based on historic piezometric information of the last two decades, however, a negative evolution could be observed, resulting a negative storage volume. So far, there is not an integral hydrogeological evaluation that determine the real condition of the groundwater resource, and that permit to planning a management of the Guadalupe Valley Aquifer. A steady-state calibration model was carried out in order to obtain the best possible match to measured levels at the Guadalupe Val[1]ley Aquifer. The contours of calculated water table elevations for January 1983 were reproduced. Generally, the comparison of the observed and calculated water table configurations have a good qualitative and quantitatively adjustment. Nowadays, it is count with a hydrogeological model that can be used for simulates the groundwater flow in the region of the Guadalupe Valley.

A groundwater flow model was developed in order to study the water table behavior and to evaluate several groundwater management alternatives in the Guadalupe Valley Aquifer, Baja California, Mexico. During the simulation of the geohydrological model of the Guadalupe Valley Aquifer is used a two-dimensional groundwater flow model and the information proportionate for the National Commission of Water, the State Public Services Commission of Ensenada, as well as the information generated by academic and research works carried out in the study zone, about the geohydrological conditions that present the Guadalupe Valle Aquifer. A groundwater flow simulator is modified and improved from the numerical point of view. Now, the groundwater flow simulator counts with subroutines to consider the effects of variables as evapotranspiration and surface water flow (or drains). Both steady-state and transient calibration were carried out in order to obtain the best possible match between the calculated and the measured water table elevation in the Guadalupe Valley Aquifer. Based on the analysis of the collected information, the beginning of the simulation period is February of 1984, and the evolution of the aquifer for a period of 21 years is calculated, using a sampling interval of one month. According to the simulator results, are reproduce the configurations of the phreatic surface for those periods with field observations. Among them are the phreatic surfaces of May 1985, June 1988, April 1990, May 1998, September 2001, March 2003, February 2004, April 2004, June 2004, October 2004 and April 2005. In general, the comparison of the phreatic surface configurations, observed and calculated, have a good adjustment qualitative and quantitatively speaking. In particular, is calculated an indicator of adjustment between the calculated data by the numerical simulator and the measured data in the field for a finite number of wells, whose result is satisfactory, according to the thesis objectives. In addition, in the whole simulation period (1984-2007) is appreciated a trend of the water table depletion in the aquifer. Validation of the simulator results is developed throughout the comparison with the measured water table elevation generated in the six sampling campaign (2004-2005) carried out as a complementary work of this thesis. Six groundwater management alternatives of the Guadalupe Valley Aquifer (2007-2025) were analyzed. Throughout the simulation of the groundwater management alternatives, the goal of the analysis was to seek the total maximum volume of groundwater discharge (that is, the optimum according to the objectives of this thesis). These alternatives are classified in four types of scenarios, among them are included the scenarios designed to evaluate the possible effects of the current groundwater management alternative, to supply in the future the current volume of groundwater if the recharge of water is reduced, to supply in the future an increment of the current volume of groundwater if the recharge of water is reduced, and to supply in the future a volume of groundwater discharge considered as sustainable. Finally, as a result of this thesis was developed an integrated hydrogeological evaluation that determines the conditions of the groundwater resource and permits planning a management of the Guadalupe Valley Aquifer. In addition, based on the simulation results can be established a technical criteria and define strategies for the management and sustainable conservation of the groundwater resources.