Treated wastewater is commonly used for park irrigation in arid zones of Mexico without considering groundwater contamination. The objective was to investigate the possibility of nitrogen compounds leaching into the groundwater and their subsequent reactions in the main types of soils. Lysimeters samples were taken to scrutinize the soil characteristics of the green areas irrigated with treated wastewater from the Northern Wastewater Treatment Plant in the city of Chihuahua. Testing samples were setup to recreate treated wastewater irrigation conditions. Nitrogen-based compounds were identified and measured before and after percolation through the soil columns. Based on the results, one meter of sand column was sufficient to remove 68 to 100% of nitrogen compounds present in the residual water. The removal of all nitrogen-based compounds as they percolate through one meter of clay soil column was not enough, due to the biochemical reactions that occur through the percolation process. Results indicate minimal risk of nitrate and nitrite leach into the aquifer, since the average static level depth is 20 m which provide broad filtration. This demonstrates an opportunity for in-situ investigations to reevaluate the standards for soil aquifer treatment recharge, based on the soil type and water quality of the area.

In intermittent drinking water distribution systems, large volumes of the water are wasted due to leaks in the distribution networks. Similarly, user service is not always satisfied in the time required to fill the storage, nor with sufficient pressure. Hence the importance of this study. Measuring the variability of pressure in the distribution network and determining the factors that influence the definition of a sufficient minimum hours of service, is a first step to change to a continuous service 24/7, in order to minimize the volumes of lost water and meet demand. 347 pressure sensors were placed in a network to detect changes in pressure and obtain data for three years. This study presents a new approach to determine the operating policy of the operating agency that provides the service intermittently. Two objectives are pursued: pressure variability – to minimize Leaks – and define the minimum hours of service. The analysis was performed using multivariate statistical techniques, including Principal Component Analysis, Correlation Matrix and ANOVA's, to explore the association between objectives. The results obtained show that the pressure distribution has a Gaussian behavior and that the hours of service has a Poisson distribution.

Groundwater is the main source of water in arid cities where precipitations are low and not evenly distributed. The combined impact of climate variability and intensive human activities has caused a substantial decline in groundwater levels. Understanding the response of groundwater levels to meteorological and anthropogenic factors is a key step to propose water management alternatives. Meteorological and groundwater data were used to design a multi-step approach to assess the influential factors on the groundwater system in the City of Chihuahua, Mexico. The analysis of historical groundwater levels and climate showed a clear increase in meteorological drought, as well as a groundwater abstraction trend since 1986. Rainfall, groundwater recharge, and groundwater level displayed a significant decrease. Overall, the groundwater depth is continuously increasing with a strong correlation with groundwater abstraction. Despite having a significant trend, the changes in land-cover, groundwater recharge, and meteorological drought were not the main factors inducing the decreased level of water in the aquifer. The continuous abstraction of groundwater from 1986 to 2010 has led to a depletion of groundwater levels from 32 to 92 m. The findings of this study lay a foundation for future water resource management in the study area.

Cities in developing countries that do not consider water resources as the basis for sustainable growth usually accept intermittent water supply (IWS) as the alternative to satisfy the demand of the population. Networks designed as constant water supply (CWS) operated as IWS hinder a safe and reliable water supply, thus, feasible alternatives to return the operation to CWS are required. This paper presents a methodology based flow/pressure control to accomplish an efficient transformation from an IWS sector to a CWS, in the City of Chihuahua, Mexico. The management of pressure at sector entrance and critical supply points leads to successful improvement of service, ensuring water availability with adequate pressure at the peak of demand, as well as reducing the supply of water volume by 58% compared to the sector operated in IWS. The methodology allowed the improvement of decision-making and operating policy for the water operating agency (WOA), fixing service deficiency, avoiding the loss of water volumes, and maintaining competent management control. Nonetheless, resistance to the transition of using automation and setting the volume/pressure consumption based on reliable data persists. The change process will be successful to the extent that the WOA efficiently channels the participation of the personnel.

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