The spatiotemporal features of land use changes and the evolution process of landscape pattern from 1980 to 2017 were investigated using historical satellite images from a Landsat Thematic Mapper (TM) for 1980, 1990, 2000, 2005, 2010 and 2017 in the wetlands of Lake Baiyangdian in the North China Plain (NCP). Landscape pattern indices were used to quantify landscape changes in wetlands, and a redundancy analysis (RDA) was conducted to analyze the driving forces and quantitatively explain the effects of human activities and natural changes on wetland fragmentation. The results showed that the total wetland area was 234.4 km² in 1980 but it decreased by 8.1% at an average decrease rate of 0.5 km² per year. The dominant transition between land use types was from natural wetlands to artificial wetlands, and wetland conversion to dry land and residential land. The RDA results suggested that agricultural activities and total population were the main driving factors affecting wetland landscape. Additionally, climate change provided a potentially favorable environment for agricultural development, due to the increased temperatures and decreased wind speeds. Additionally, governmental policy changes and dam construction also played the roles in land use changes.

Vertical line source irrigation is a water-saving irrigation method for enhancing direct water and nutrient delivery to the root zone, reducing soil evaporation and improving water and nutrient use efficiency. To identify its influencing factors, we performed computer simulations using the HYDRUS-2D software. The results indicate that for a given soil, the line source seepage area, but not the initial soil water content and buried depth, has a significant effect on the cumulative infiltration. We thus proposed a simplified method, taking into account the seepage area for predicting the cumulative infiltration based on the Philip model. Finally, we evaluated the accuracy of the simplified method using experimental data and found the cumulative infiltrations predicted by the simplified method were in very good agreement with the observed values, showing a low mean average error of 0.028–0.480 L, a root mean square error of 0.043–0.908 L, a percentage bias of 0.321–0.900 and a large Nash-Sutcliffe coefficient close to 1.0 (NSE ≥ 0.995). The results indicate that this simplified infiltration model, for which the only emitter parameter required is the seepage area, could provide a valuable and practical tool for irrigation design.

Numerical simulations were carried out with HYDRUS-2 D to investigate the influence of soil texture, initial water content, film hole diameter and water depth on cumulative infiltration from a film hole. Soil texture, film hole diameter and water depth are the dominant influencing factors. Philip infiltration model was used to fit the simulated results of the dominant influencing factors. For the same soil, the sorptivity (s) is a power function relationship with film hole diameter, while the steady infiltration rate (a) is a power function relationship with film hole diameter and water depth. On that basis, the calculation formulas for predicting s and a were established, and a simplified film hole infiltration model including the film hole diameter and water depth was proposed. The effectiveness of the model was verified by laboratory experiments and literature data. The predicted values of the model were in good agreement with the experimental observations. The model parameters can be determined only by a set of film hole infiltration experiment, which simplifies the experimental design and can be used as a tool for irrigation engineers or farmers to estimate cumulative infiltration.

Studying the dimensions of soil wetting pattern (SWP) is important for designing optimal film hole irrigation (FHI) systems. HYDRUS-2D was used to simulate the dynamic changes of SWP under different soil texture (ST), initial moisture content (θ_i), film hole diameter (D) and irrigation water head (H) during FHI. The results indicate that ST and D, rather than H and θ_i, have a significant impact on SWP. Based on the simulation results, a power function was utilized to fit the horizontal radius (X) and vertical depth (Y) of SWP. The relationship between the fitting parameters and D, H, and saturated hydraulic conductivity (K_s) was analysed. An empirical model for estimating the X and Y was produced. Data from laboratory experiments and published studies were adopted to assess the empirical model. The results showed that the X and Y calculated using the empirical model were highly consistent with the observed data. The values of root mean square error vary from 0.355 to 1.107 cm and Nash Sutcliffe efficiency is closed to 1.0. In this study, the only parameter required for the empirical model is K_s, which can provide valuable and practical tools for FHI design.

We used a fixed-bed flume test and ultrasonic sensor measurement technology to study the evolution of the characteristics of thin-layer flow roll waves on a sloped surface. The results indicated that there was a positive correlation between the velocity of the roll wave and the Reynolds number when the energy slope and roughness were small. In addition, the amplitude of the increase gradually decreased with increases in roughness, and the height of the roll waves showed a single-hump trend of change. When the roughness was relatively small, the frequency of the roll waves increased as the Reynolds number increased, and the ratio of the wavelength to the water depth gradually decreased. As the energy slope increased, both the wave velocity and frequency of the roll waves gradually increased; they peaked when the energy slope was 0.3420. We found that the dominant factors that affected different roll-wave characteristic parameters varied. The roughness of the bed had a relatively prominent impact on the velocity of the roll waves, but the energy slope had a greater effect on the height of the roll waves.

Shanxi province is located in the middle reach of the Yellow River, which is also the important energy and chemical industry base of China. Water resources shortage and over exploitation of groundwater is serious in Shanxi Province. Therefore, Shanxi has promoted the construction of water resources monitoring system since 2010. The monitoring system consists of 262 water source areas, 865 water intake sites for municipal water supply, 115 irrigation areas, 43 river control sections, 259 sewage outlets, and 504 groundwater gauge points. All the monitoring datasets from the above points are integrated into a water resources management information system (MIS). Based on the MIS, a decision support system (DSS) is built for routine management and emergency water regulation. The DSS is divided into two levels. The top level, also named provincial level, can access all the data of the monitoring points and remote control nodes. It is a data storage center, and also a decision-making and command center. The bottom level, called municipal level, can only access the monitoring data of the points under its jurisdiction. The bottom level is also responsible for local water resources dispatch in the scope of authority. The MIS and DSS have greatly improved the scientific and informatization ability of water resources management, and the water shortage situation and the over exploitation of groundwater in Shanxi Province have been greatly alleviated by optimal scheduling based on the MIS and DSS