ABSTRACT The Lake Ypoa system, comprised of the three major water bodies Ypoa, Cabral and Vera, is located within one of the cratons of the Oriental region, the Tebicuary River, and is highly influenced by the dynamics of the rivers Paraguay and Paraná. During the work carried out, the bathymetric studies have shown the shallow depth of each of these water bodies. Studies of the dynamics of the floating islands of vegetation that cover a large portion of the three water bodies suggest that they are in ongoing evolution, consolidating themselves more and more, and in some cases even adjoining themselves to the mainland. Given these facts, the proposed hypothesis of redefining the limits of the Lake Ypoa system as a single body of water divided by the floating islands of vegetation becomes more plausible, as opposed to the three separated bodies; this concept was also illustrated in the 19th century cartography of the region. Bearing in mind this is a protected area, it is imperative to redefine the boundaries of this water system including the three water bodies in a single lagoon system and incorporating the floating islands of vegetation as the sites where most of the biodiversity associated with wetlands is concentrated. | RESUMEN El complejo conocido como lago Ypoá, con tres espejos de aguas sobresalientes Ypoá, Cabral y Verá se encuentran enmarcados dentro de uno de los cratones de la región Oriental, el del río Tebicuary y muy influenciado por la dinámica de los ríos Paraguay y Paraná. Durante el trabajo realizado, los análisis batimétricos han demostrado la escasa profundidad de cada uno de estos cuerpos de agua. Los estudios de la dinámica de los embalsados que cubren una gran parte de los tres espejos sugieren que estos se encuentran en plena evolución, consolidándose cada vez más y en algunos casos ya uniéndose a tierra firme. Ante estos hechos, la hipótesis planteada de redefinir los límites del lago Ypoá y limitarlo a un solo cuerpo de agua en vez de tres, separados por las masas de embalsados, cobra mucha fuerza tal y como lo indica la cartografía del siglo XIX de la región. Por ser un área protegida, urge redefinir los límites del mismo, uniendo los tres espejos de agua en uno solo e incorporando dentro de estos a las masas de embalsados, sitios en donde se concentra mayoritariamente la biodiversidad asociada al agua.

Beijing is a major metropolis in China, which shows characteristics of significant land subsidence because of long-term overexploitation of groundwater. Since the South-to-North Water Diversion Project Central Route was first operated in December 2014, it has provided Beijing with a new source of water. In this study, a variety of monitoring data has been used to analyze the changes in the groundwater flow field and land subsidence when comparing the conditions before and after the Water Diversion Project started, and to study the stress-strain characteristics of the soil layers at different depths under different water-level-change modes. Meanwhile, causes of the large residual deformation and hysteresis deformation of the cohesive soils are discussed. The study reveals that after the operation of the Water Diversion Project, the area of the groundwater depression cone and the rate of land subsidence in the Beijing Plain showed an overall decreasing trend. The deformation characteristics of different lithological soil layers under different water-level-change modes can be summarized into four categories. The sand layer is mainly characteristic of elastic deformation. The cohesive soil layers of different depths have elastic, plastic and creep deformation, and the viscoelastic-plastic characteristics are obvious. The large residual deformation and hysteresis deformation of the cohesive soil layer are mainly caused by two factors: firstly, the inelastic water storage rate is greater than the elastic water storage rate, and secondly, the cohesive soil has weak permeability.

Evolution of soil-water movement patterns following rare and extreme rainfall events in arid climates is not well understood, but it has significant effects on water availability for desert plants and on the hydrological cycle at small scale. Here, field data and the Hydrus-1D model were used to simulate the mechanisms of soil water and vapor transport, and the control factors associated with temporal variability in the soil water and temperature were analyzed. The results showed that thermal vapor transport with a no rainfall scenario determined daily variability in water content at the soil surface. During rainfall, isothermal liquid water fluctuated as a result of dry sandy soils and matric potential in the upper soil (0–25 cm), and thermally driven vapor played a key role in soil-water transport at 40–60 cm soil depth. After an extreme rainfall event, thermal vapor flux increased and accounted for 11.8% of total liquid and vapor fluxes in daytime with a steep temperature gradient; this was very effective in improving long-term soil-water content after the rain. The simulated results revealed that thermal water vapor greatly contributed to the soil-water balance in the vadose zone of desert soil. This study provided an alternative approach to describing soil-water movement processes in arid environments, and it increased understanding of the availability of water for a desert plant community.

The Ica area of south-eastern Peru has evolved rapidly since the late 1990s into the most advanced agricultural development in the country. The intensive use of waterwells for year-round irrigation, primarily of asparagus, is the basis for an export industry worth about US$ 6,000 M/a, but one which is threatened by serious groundwater sustainability concerns. The public water-resource administration and private agricultural developers are beginning to confront the problem, which has already had a significant social cost, through developing measures to improve the groundwater balance whilst assuring agricultural production. This report presents the long-term evolution of land management and groundwater use in the area, and considers the feasibility of applying an adaptive and integrated water resources management (IWRM) approach to the system, with particular attention to managed aquifer recharge techniques.

Nitrate pollution from agricultural sources is one of the biggest issues facing groundwater management in the European Union (EU). During the last three decades, tens of nitrate vulnerable zones (NVZ) have been designated across the EU, aiming to make the problem more manageable. The Gallocanta Groundwater Body in NE Spain was declared as an NVZ in 1997, and after more than 20 years, significant improvements in water quality were expected to be observed. In the present study, the spatiotemporal trend of nitrate concentration within the Gallocanta NVZ in the last 38 years was assessed, and the effectiveness of the NVZ implementation was tested. Data from the official Ebro Basin Confederation monitoring network from 1980 to 2018 were used, and the results showed an increasing but fluctuating trend in nitrate concentration since 1980. Although a slight improvement was detected after the NVZ designation in 1997, the low rate of improvement would take decades to reach desirable levels in most of the area. The lack of update and control of action programmes, the inappropriate NVZ delimitation, and the influence of natural factors seem to be the reasons for the failure of the nitrate reduction measures. Currently, nitrate pollution and groundwater management are a matter of concern for the EU, so given the recurring problems in water supply in the area and the nonfulfillment of the goal of good quality status, more demanding measures are needed to be implemented in the short term.