Estas MPM siempre se han revisado en el contexto del proyecto SHui, que cubre diferentes regiones agroclimáticas en Europa y China y estos sistemas agrícolas: 1- Cultivos arbóreos de secano. 2- Cultivos arbóreos de regadío. 3- Rotaciones a base de cereales en condiciones de secano. 4- Rotaciones a base de cereales bajo riego. En cuanto al uso de agua para riego, este documento también aborda el uso de agua de baja calidad, incluidas las aguas residuales, y el uso de agua reciclada para riego. | Traducción y edición en español: Federico Julián Fuentes y José Alfonso Gómez, Grupo Operativo Cereal Agua. | Versión en inglés disponible en: http://dx.doi.org/10.20350/digitalCSIC/13964 | Versión en chino disponible en: http://hdl.handle.net/10261/253611 | Este documento es la traducción al castellano de la versión original en inglés fruto de la colaboración entre el Grupo Operativo Nacional Cereal Agua (de la EIP-Agri) y el proyecto SHui (del programa H2020 de la Comisión Europea). El mismo proporciona una revisión integral de las Mejores Prácticas de Manejo (MPM) para el optimizar el uso sostenible de los recursos suelo y agua en los sistemas agrícolas dentro del contexto del proyecto SHui. Este documento, que además de la versión original inglesa ha sido traducido al español y al chino, podría utilizarse para: 1- Proporcionar a cualquier lector una visión general de la descripción técnica de las opciones disponibles de MPM para optimizar el uso sostenible de los recursos suelo y agua. 2- Identificar cómo se definen y se regulan las MPM en relación con los grandes instrumentos regulatorios, en particular la Política Agrícola Común (PAC), a fin de proporcionar orientación sobre escenarios en que se implementaran esas MPM, así como facilitar la formulación recomendaciones para su mejor implementación por diferentes agentes. 3- Proporcionar un marco común, tanto dentro del proyecto como para los usuarios externos, para la definición de MPM utilizando una terminología estandarizada, así como una evaluación de cómo algunos de los modelos hidrológicos más comunes pueden usarse, o no, para introducir el efecto de estas MPM sobre estudios de análisis de escenarios en los que se introduzcan algunas de estas prácticas. | Grupo Operativo Cereal Agua. Para su constitución, al grupo le ha sido concedida una subvención del Fondo Europeo Agrícola de Desarrollo Rural en el marco del Programa Nacional de Desarrollo Rural 2014-2020 del Ministerio de Agricultura, Pesca y Alimentación. La creación de los Grupos Operativos de ámbito nacional ha sido posible a través de la Asociación Europea para la Innovación en materia de productividad y sostenibilidad agrícola (AEI-AGRI). La creación y funcionamiento del grupo operativo supraautonómico CEREAL-AGUA está cofinanciada en un 80% con el Fondo Europeo Agrícola de Desarrollo Rural (FEADER) de la Unión Europea, y en un 20% por el Ministerio de Agricultura, Pesca y Alimentación en el marco del Programa Nacional de Desarrollo Rural 2014-2020, siendo la inversión total de 507.930,00 €.-- Soil Hydrology research platform underpinning innovation to manage water scarcity in European and Chinese cropping systems. SHui. Comisión Europea. Identificador del acuerdo de subvención 773903. | Peer reviewed

A field experiment was carried out in southern Xinjiang, China, to reveal soil-water flow pattern beneath a combined plastic-mulch (film) and drip-irrigation system using brackish water. The soil-water flow system (SWFS) was characterized from soil surface to the water table based on observed spatio-temporal distribution of total soil-water potential, water content and electric conductivity. Root suction provided a strong inner sink. The results indicated that SWFS determined the soil salinity and moisture distribution. Drip-irrigation events could leach excess salts from the root zone and provide soil conditions with a tolerable salinity level that supports the growth of cotton. High-salinity strips were formed along the wetting front and at the bare soil surface. Hydrogeology conditions, irrigation regime, climate, plant growth and use of mulch would affect potential sources and sinks, boundary conditions and the size of the SWFS. At depth 0–60 cm, the soil salinity at the end of the irrigation season was 1.9 times that at the beginning. Beneath the mulch cover, the soil-water content in the ‘wide rows’ zone (55 cm between the two rows with no drip line) was higher than that in the ‘narrow rows’ zone (15 cm between the two rows with a drip line) due to the strong root-water uptake. The downward water flow below the divergent curved surface of zero flux before irrigation, and the water-table fluctuation with irrigation events, indicated that excessive irrigation occurred.

The widely used groundwater flow model MODFLOW offers a range of software packages to simulate the interaction between streams and groundwater in aquifer systems. However, these existing packages lack a general method to address the chaotic simulation sequences of stream segments and require these segments to be ordered by modelers as input to the code. Therefore, it is challenging to simulate a stream network divided into a large number of segments such as a canal irrigation system. In this study, the Streamflow Automatic Routing (SAR) package was developed, and an effective method is proposed to automatically determine the segment simulation sequence. The stream segment order in the SAR input file is arbitrary, which allows modifications of the stream network by removing segments directly and adding segments at the end of the segment group. This mainly includes two processes: scanning all the outlet channels of the water system and calling the recursive algorithm for each outlet channel of the water system. The SAR package was tested using a hypothetical stream–aquifer system and applied to a complex flow field in Aiding Lake of Turpan Basin, China. In the results, a close fitting between the simulation and observations shows that the SAR package precisely simulated the exchange flux between the steams and aquifer. The SAR package can significantly improve the efficiency of simulations in a complex stream network, and it can be widely used as a subroutine package of MODFLOW in agricultural irrigation areas where rivers and canals are interlaced.

Investigation of surface water and groundwater interaction (SW–GW interaction) provides basic information for regional water-resource protection, management, and development. In this survey of a 10-km-wide area along both sides of the Songhua River, northeast China, the hydrogeochemical responses to different SW–GW interactions were studied. Three types of SW–GW interactions were identified—“recharge”, “discharge”, and “flow-through”—according to the hydraulic connection between the surface water and groundwater. The single factor index, principal component analysis, and hierarchical cluster analysis of the hydrogeochemistry and pollutant data illuminated the hydrogeochemical response to the various SW–GW interactions. Clear SW–GW interactions along the Songhua River were revealed: (1) upstream in the study area, groundwater usually discharges into the surface water, (2) groundwater is recharged by surface water downstream, and (3) discharge and flow-through coexist in between. Statistical analysis indicated that the degree of hydrogeochemical response in different types of hydraulic connection varied, being clear in recharge and flow-through modes, and less obvious in discharge mode. During the interaction process, dilution, adsorption, redox reactions, nitrification, denitrification, and biodegradation contributed to the pollutant concentration and affected hydrogeochemical response in the hyporheic zone.

Identification and quantification of groundwater and surface-water interactions provide important scientific insights for managing groundwater and surface-water conjunctively. This is especially relevant in semi-arid areas where groundwater is often the main source to feed river discharge and to maintain groundwater dependent ecosystems. Multiple field measurements were taken in the semi-arid Bulang sub-catchment, part of the Hailiutu River basin in northwest China, to identify and quantify groundwater and surface-water interactions. Measurements of groundwater levels and stream stages for a 1-year investigation period indicate continuous groundwater discharge to the river. Temperature measurements of stream water, streambed deposits at different depths, and groundwater confirm the upward flow of groundwater to the stream during all seasons. Results of a tracer-based hydrograph separation exercise reveal that, even during heavy rainfall events, groundwater contributes much more to the increased stream discharge than direct surface runoff. Spatially distributed groundwater seepage along the stream was estimated using mass balance equations with electrical conductivity measurements during a constant salt injection experiment. Calculated groundwater seepage rates showed surprisingly large spatial variations for a relatively homogeneous sandy aquifer.

In some areas close to a reverse fault with significant vertical displacement, or the boundary of a mining area in multi-layer rock and the boundary of perched water, the phreatic water-level changes abruptly from one side of the fault or boundary to the other. There is no direct hydraulic connection between the two sides and a groundwater fall occurs across the fault or boundary. This groundwater fall cannot be easily handled by the modules available in MODFLOW. Semi-analytical solutions were derived for water discharge from the upstream to the downstream side of the fault or boundary, and verified by air-water two-phase numerical simulation. The numerical results show that the derived semi-analytical solutions can be used to accurately estimate the groundwater flux at the fault even though the unsaturated zone is not considered. A module package, GWF, was developed to simulate the groundwater fall, which can be embedded directly into MODFLOW. A theoretical example is presented to show how the package GWF is used to simulate perched water. This package was also applied successfully to build a regional groundwater model of the Urumqi River Basin, Xinjiang, China, and the simulation results showed good agreement with the local hydrogeologic conditions.

The ungauged Sugan Lake Basin represents a candidate area for development of a water transfer scheme to satisfy the water requirement of Dunhuang city in northwestern China. In this work, multisource data, including river runoff, groundwater levels and remote-sensing data, and field investigation records, were collected and analyzed. A three-dimensional groundwater flow model was constructed using FEFLOW software to predict the potential influence of the transfer project on the groundwater system. Results show that infiltration from the Great Harten River is the main driving factor of groundwater-level fluctuation and groundwater recharge. Scenario analysis under four water transfer conditions found that the drawdown of groundwater gradually decreases from east to west. If the water transfer scale reaches 1.2 × 10⁸ m³/a, after 100 years, the maximum drawdown of groundwater is noted at 68.02 m, and the flow rate of the Middle Spring reduces by 25.7%. In the western wetland, the area over which the groundwater level is lowered by more than 4 m is 10.21 km², and natural succession may occur or vegetation cover may decline. The results of this study will aid in water resource planning based on a rational amount of water transfer, and provide further protection of the wetland ecology.

Farmlands have gradually been replaced by apple orchards in Shaanxi province, China, and there will be a risk of severe soil-water-storage deficit with the increasing age of the apple trees. To provide a theoretical basis for the sustainable development of agriculture and forestry in the Loess Plateau, soil water content in a 19-year-old apple orchard, a 9-year-old apple orchard, a cornfield and a wheat field in the Changwu Tableland was investigated at different depths from January to October 2014. The results showed that: (1) the soil moisture content is different across the soil profile—for the four plots, the soil moisture of the cornfield is the highest, followed by the 9-year-old apple orchard and the wheat field, and the 19-year-old apple orchard has the lowest soil moisture. (2) There are varying degrees of soil desiccation in the four plots: the most serious degree of desiccation is in the 19-year-old apple orchard, followed by the wheat field and the cornfield, with the least severe desiccation occurring in the 9-year-old apple orchard. Farmland should replace apple orchards for an indefinite period while there is an extremely desiccated soil layer in the apple orchard so as to achieve the purpose of sustainable development. It will be necessary to reduce tree densities, and to carry out other research, if development of the economy and ecology of Changwu is to be sustainable.

Land subsidence is common in some regions of China. Various eco-environmental problems have arisen due to changes in water–rock interactions in these subsided areas, for which a comprehensive understanding of the hydrogeological setting is needed. This paper presents the general status of land subsidence in three typical subsided areas of China through the compilation of relevant data, and reviews some typical changes in the water–rock interactions in subsided areas along with related eco-environmental issues. It is found that the subsidence development and distribution are controlled by the groundwater-withdrawal intensity externally, and by the thickness and compressibility of unconsolidated sediments internally. The physical changes and related effects of water–rock interactions in subsided areas include: (1) the decreased ground elevation that caused floods, waterlogged farmland, etc.; (2) the differential subsidence that caused ground fissures; and (3) the change of seepage field that caused substantial reduction of the water resource. Chemically, the changes and related effects of water–rock interactions include: (1) the change to the chemical environment or processes due to the hydrogeologic structure alteration, which caused groundwater pollution; and (2) hydrologic mixing (seawater intrusion, artificial recharge; exchange with adjacent aquifers or aquitards), which degraded the groundwater quality. Further research on the subsided areas in China is suggested to reveal the mechanisms regarding biological and gaseous (meteorological) changes from the perspective of interacting systems among water, rocks, biological agents and gases.

Correct understanding of groundwater/surface-water (GW–SW) interaction in karst systems is of greatest importance for managing the water resources. A typical karst region, Fangshan in northern China, was selected as a case study. Groundwater levels and hydrochemistry analyses, together with isotope data based on hydrogeological field investigations, were used to assess the GW–SW interaction. Chemistry data reveal that water type and the concentration of cations in the groundwater are consistent with those of the surface water. Stable isotope ratios of all samples are close to the local meteoric water line, and the ³H concentrations of surface water and groundwater samples are close to that of rainfall, so isotopes also confirm that karst groundwater is recharged by rainfall. Cross-correlation analysis reveals that rainfall leads to a rise in groundwater level with a lag time of 2 months and groundwater exploitation leads to a fall within 1 month. Spectral analysis also reveals that groundwater level, groundwater exploitation and rainfall have significantly similar response periods, indicating their possible inter-relationship. Furthermore, a multiple nonlinear regression model indicates that groundwater level can be negatively correlated with groundwater exploitation, and positively correlated with rainfall. The overall results revealed that groundwater level has a close correlation with groundwater exploitation and rainfall, and they are indicative of a close hydraulic connection and interaction between surface water and groundwater in this karst system.