An improved method for calculating slope length (λ) and the LS parameters of the Revised Universal Soil Loss Equation for large watersheds

The Universal Soil Loss Equation (USLE) and its revised version (RUSLE) are often used to estimate soil erosion at regional landscape scales. USLE/RUSLE contain parameters for slope length factor (L) and slope steepness factor (S), usually combined as LS. However a major limitation is the difficulty in extracting the LS factor. Methods to estimate LS based on geographic information systems have been developed in the last two decades. L can be calculated for large watersheds using the unit contributing area (UCA) or the slope length (λ) as input parameters. Due to the absence of an estimation of slope length, the UCA method is insufficiently accurate. Improvement of the spatial accuracy of slope length and LS factor is still necessary for estimating soil erosion. The purpose of this study was to develop an improved method to estimate the slope length and LS factor. We combined the algorithm for multiple-flow direction (MFD) used in the UCA method with the LS-TOOL (LS-TOOLSFD) algorithms, taking into account the calculation errors and cutoff conditions for distance, to obtain slope length (λ) and the LS factor. The new method, LS-TOOLMFD, was applied and validated in a catchment with complexly variable slopes. The slope length and LS calculated by LS-TOOLMFD both agreed better with field data than with the calculations using the LS-TOOLSFD and UCA methods, respectively. We then integrated the LS-TOOLMFD algorithm into LS-TOOL developed in Microsoft's.NET environment using C# with a user-friendly interface. The method can automatically calculate slope length, slope steepness, L, S, and LS factor, providing the results as ASCII files that can be easily used in GIS software and erosion models. This study is an important step forward in conducting accurate large-scale erosion evaluation

Quality of terrestrial data derived from UAV photogrammetry : A case study of Hetao irrigation district in northern China

Most crops in northern China are irrigated, but the topography affects the water use, soil erosion, runoff and yields. Technologies for collecting high-resolution topographic data are essential for adequately assessing these effects. Ground surveys and techniques of light detection and ranging have good accuracy, but data acquisition can be time-consuming and expensive for large catchments. Recent rapid technological development has provided new, flexible, high-resolution methods for collecting topographic data, such as photogrammetry using unmanned aerial vehicles (UAVs). The accuracy of UAV photogrammetry for generating high-resolution Digital Elevation Model (DEM) and for determining the width of irrigation channels, however, has not been assessed. A fixed-wing UAV was used for collecting high-resolution (0.15 m) topographic data for the Hetao irrigation district, the third largest irrigation district in China. 112 ground checkpoints (GCPs) were surveyed by using a real-time kinematic global positioning system to evaluate the accuracy of the DEMs and channel widths. A comparison of manually measured channel widths with the widths derived from the DEMs indicated that the DEM-derived widths had vertical and horizontal root mean square errors of 13.0 and 7.9 cm, respectively. UAV photogrammetric data can thus be used for land surveying, digital mapping, calculating channel capacity, monitoring crops, and predicting yields, with the advantages of economy, speed and ease.</p

Pesticide residues with hazard classifications relevant to non-target species including humans are omnipresent in the environment and farmer residences

Intensive and widespread use of pesticides raises serious environmental and human health concerns. The presence and levels of 209 pesticide residues (active substances and transformation products) in 625 environmental samples (201 soil, 193 crop, 20 outdoor air, 115 indoor dust, 58 surface water, and 38 sediment samples) have been studied. The samples were collected during the 2021 growing season, across 10 study sites, covering the main European crops, and conventional and organic farming systems. We profiled the pesticide residues found in the different matrices using existing hazard classifications towards non-target organisms and humans. Combining monitoring data and hazard information, we developed an indicator for the prioritization of pesticides, which can support policy decisions and sustainable pesticide use transitions. Eighty-six percent of the samples had at least one residue above the respective limit of detection. One hundred residues were found in soil, 112 in water, 99 in sediments, 78 in crops, 76 in outdoor air, and 197 in indoor dust. The number, levels, and profile of residues varied between farming systems. Our results show that non-approved compounds still represent a significant part of environmental cocktails and should be accounted for in monitoring programs and risk assessments. The hazard profiles analysis confirms the dominance of compounds of low-moderate hazard and underscores the high hazard of some approved compounds and recurring “no data available” situations. Overall, our results support the idea that risk should be assessed in a mixture context, taking environmentally relevant mixtures into consideration. We have uncovered uncertainties and data gaps that should be addressed, as well as the policy implications at the EU approval status level. Our newly introduced indicator can help identify research priority areas, and act as a reference for targeted scenarios set forth in the Farm to Fork pesticide reduction goals

Flood analysis in the Wei River Basin

Floods are considered to be one of the most destructive natural hazards on Earth. Apart from precipitation as the main driving factor for flood occurrence, there is increased recognition that human activities also largely influence the occurrence and impacts of floods. The Wei River Basin in China has suffered from floods for decades due to its monsoon climate with intensive summer rainfall. With the rapid development of the economy and population growth, land use and the water cycle have been altered due to the demands for resources redistribution. Consequently, the Wei River Basis is under pressure from both climate and anthropogenic changes. This thesis aims to bring a comprehensive understanding of the factors causing flood occurrence in the basin and propose an integrated management tool for flood analysis under the complex environment in the Wei River Basin. Chapter 1 describes the general factors and processes leading to flood occurrence with respect to meteorological, biophysical and anthropogenic aspects. Chapter 2 starts with the introduction of a framework approach for understanding these factors and their importance regarding contribution to flood occurrence in the Wei River Basin, and then presents the results of our application of this approach. The framework approach uses a set of methods to answer the questions why, where, when, and how flooding occurs and includes Conditional Inference Tree (CIT), cross correlation and double mass curves analyses. The results revealed that the dam construction period was the most important factor (why), and the Western upstream regions of the Wei River contributed the most to the flooding of the downstream floodplain (where). The effect of the periods of dam construction on the time lag change (when) and the precipitation-discharge relationship (how) were also analysed by the cross-correlation analysis and double mass curves analysis, respectively. Being able to bring both numeric and non-numeric factors into the analyses, the CIT analysis proved to be a powerful tool for unravelling complex causes leading to flood occurrence. The insights gained in this chapter can be further applied to understanding of flooding schemes in other regions and to derive targeted flood mitigation measures in the Wei River Basin. LISFLOOD modelling was then calibrated and validated, the results of which are presented in Chapter 3. The urgent need for the development of an integrated approach to evaluating the impacts of climate change, land use change and river alteration as well on the occurrence of hydrological extreme events drove us to choose a physically-based distributed hydrological model as a solid base for accurate discharge simulation. Using globally available land cover, soil, vegetation as well as geographical datasets, combined with local observed meteorological gauging data as input, the application of the LISFLOOD model performed well in simulating the discharge at the outlet station on the floodplain. Being a distributed model, LISFLOOD enabled prediction of discharge at the outlets of 17 tributaries draining into the main river. The simulated discharge from these outlets were analysed regarding their contribution to the total runoff as well as for individual flood events. This study is the first application of the LISFLOOD model for a semi-arid region in China for flood discharge analysis, and has shown to be a sophisticated and reliable tool for catchment scale land and water management planning related to flood occurrence and dynamics. Chapter 4 reports on the evaluation of the usability of various freely available datasets for discharge simulation with LISFLOOD. The quality of the meteorological data inputs into the hydrological model is of vital importance for understanding the hydrological regime as well as for analysis and prediction of hydrological extremes. Many efforts have been made to develop globally freely available meteorological reanalyses data especially for data scarce regions. We evaluated ten globally freely available datasets for discharge simulation by using them as input for the LISFLOOD model and comparing results between and with observed meteorological data and discharge in Chapter 3. The result was rather disappointing and suggested that none of the evaluated datasets can be applied directly for daily discharge simulation by the LISFLOOD model. This is unfortunate as accurate simulation of discharge is essential for flood analysis under climate change circumstances. An in-depth analysis of the performance of precipitation and temperature data against the observations was then conducted in an attempt to improve the simulation of the datasets. In Chapter 5 the impact of anthropogenic changes in the basin on flood peak discharge is investigated. It is increasingly recognized that the effects of flood events are greatly influenced by the changes that humans have imposed on the environment and river systems. In the Wei River Basin of China there have been tremendous changes including land use and soil and water alterations under the pressure of population growth and water resource scarcity. To investigate the potential of LISFLOOD for assessing the effects of anthropogenic activities on base flow and peak flow, three categories of scenarios regarding human intervention in the basin were evaluated against a business as usual scenario using the simulated discharge from the LISFLOOD model: 1) natural conditions of the basin, 2) additional reservoirs constructed in different sub-catchments, and 3) water transfer from an adjacent catchment via a pipeline providing a fixed daily inflow. The results of the scenarios are presented for three strategically important cities located on the floodplain. Compared to the business as usual case, the minimum base flow at the three cities increased 54 fold on average with additional dam/reservoir construction, and 41 fold with the pipeline scenario, while with the 1980 land use scenario minimum base flow decreased by 0.8 times. Regarding peak flows, additional reservoirs could reduce them and the water transfer plan would not increase them. The results for the scenarios with the application of the LISFLOOD model cross validated the feasibility of using a modelling approach for catchment flood discharge management as well as providing insight for future policymaking processes. Last but not the least, Chapter 6 concludes the whole thesis with discussion of the findings from different perspectives as well as provision of outlooks and recommendations regarding the application of hydrological modelling for evaluation of scenarios for regional flood mitigations and related societal impacts. This thesis has increased knowledge and furthered the science regarding flood analysis in the Wei River Basin and how to address the increasing pressure from both climate and anthropogenic changes. </p

Urban water consumption and its influencing factors in China : Evidence from 286 cities

Factors that affect water consumption should be identified to develop effective public policies. However, factors influencing domestic water consumption in cities in China, particularly on a national scale, are unclear. In this study, urban water consumption and its influencing factors in 286 municipal cities in China were analysed by using conditional inference trees and the random forest method. Results showed that water consumption (per capita per day) of 130 cities had changed significantly (decrease: 69; increase: 61) from 2000 to 2015. Of the 286 cities studied, 112 were classified as low-water consumption cities with water consumption below 70 L per capita per day. In addition, water consumption per capita per day in China was found to be highly affected by meteorological factors, socioeconomic status, water supply and conservation factors. The factors influencing water consumption also varied across different cities. In high-consumption cities, water consumption per capita per day was strongly influenced by precipitation, water conservation investment, water heater for showering or bathing per household and gross domestic product per capita. In medium- and low-consumption cities, water consumption per capita per day was affected by water supply capacity and socioeconomic status, including gross domestic product per capita, education received and Engel's coefficient. Significant disparities in these factors suggest that different policies regarding water consumption should be implemented across China. In high-consumption cities, investment in water conservation should be continued to ensure sustainable use by reducing water consumption. In low-consumption cities, water supply capacity should be improved to guarantee water availability for basic health and hygiene requirements

Diversification and Management Practices in Selected European Regions. A Data-analysis of Arable Crops Production and soil organic carbon

This data set contains a data-mining performed to assess the impact of intercropping, tillage and fertilizer type on soil organic carbon and crop yield in arable crops from four selected European pedoclimatic regions and typical cropping systems in the Atlantic, Boreal, Mediterranean North, and Mediterranean South regions. A further meta-analysis was performed with these data. These data correspond to the open-access articles: - Diversified Arable Cropping Systems and Management Schemes in Selected European Regions Have Positive Effects on Soil Organic Carbon Content. Agriculture 2019, 9, 261. https://www.mdpi.com/2077-0472/9/12/261?type=check_update&version=2 - Diversification and Management Practices in Selected European Regions. A Data-analysis of Arable Crops Production. Agronomy 2020, 10, 297; doi:10.3390/agronomy10020297. https://www.mdpi.com/2073-4395/10/2/297 - Deficit Drip Irrigation in Processing Tomato Production in the Mediterranean Basin: A Data Analysis for Italy. Agriculture 2019, 9, 79; doi:10.3390/agriculture9040079. https://www.mdpi.com/2077-0472/9/4/79?type=check_update&version=2 The research and publications have been funded by he European Commission Horizon 2020 project Diverfarming [grant agreement 728003]

Diversification and Management Practices in Selected European Regions. A Data Analysis of Arable Crops Production

15 Pags.- 6 Figs. © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).In the European Union, various crop diversification systems such as crop rotation, intercropping and multiple cropping, as well as low-input management practices, have been promoted to sustain crop productivity while maintaining environmental quality and ecosystem services. We conducted a data analysis to identify the benefits of crop associations, alternative agricultural practices and strategies in four selected regions of Europe (Atlantic, Boreal, Mediterranean North and Mediterranean South) in terms of crop production (CP). The dataset was derived from 54 references with a total of 750 comparisons and included site characteristics, crop information (diversification system, crop production, tillage and fertilization management) and soil parameters. We analyzed each effect separately, comparing CP under tillage management (e.g., conventional tillage vs. no tillage), crop diversification (e.g., monoculture vs. rotation), and fertilization management (e.g., mineral fertilization vs. organic fertilization). Compared with conventional tillage (CT), CP was higher by 12% in no tillage (NT), in fine- and medium-textured soils (8–9%) and in arid and semiarid sites located in the Mediterranean Region (24%). Compared to monoculture, diversified cropping systems with longer crop rotations increased CP by 12%, and by 12% in soils with coarse and medium textures. In relation to fertilization, CP was increased with the use of slurry (40%), and when crop residues were incorporated (39%) or mulched (74%). Results showed that conversion to alternative diversified systems through the use of crop rotations, with NT and organic fertilization, results in a better crop performance. However, regional differences related to climate and soil-texture-specific responses should be considered to target local measures to improve soil management.The work was funded within the Diverfarming project “Crop diversification and low-input farming across Europe: from practitioners’ engagement and ecosystems services to increased revenues and value chain organisation”, a European Union’s Horizon 2020 Programme for Research & Innovation, under grant agreement no 728003.Peer reviewe

Diversification and Management Practices in Selected European Regions. A Data-analysis of Arable Crops Production and soil organic carbon

This data set contains a data-mining performed to assess the impact of intercropping, tillage and fertilizer type on soil organic carbon and crop yield in arable crops from four selected European pedoclimatic regions and typical cropping systems in the Atlantic, Boreal, Mediterranean North, and Mediterranean South regions. A further meta-analysis was performed with these data

Effects of elevated CO₂ and drought on the microbial biomass and enzymatic activities in the rhizospheres of two grass species in Chinese loess soil

Elevated CO2 and drought are key consequences of climate change and affect soil processes and plant growth. This study investigated the effects of elevated CO2 and drought on the microbial biomass and enzymatic activities in the rhizospheres of Bothriochloa ischaemum and Medicago sativa in loess soil. Drought exerted significant species-specific negative effects on root and shoot biomass and microbial properties except for the soil basal respiration in the rhizospheres of B. ischaemum and M. sativa. Increased CO2 exerted weak effects on plant biomass and enzymatic activities but demonstrated significant effects on the amounts of carbon and nitrogen in soil microbial biomass, basal respiration, substrate-induced respiration, and the metabolic quotients in the rhizospheres of M. sativa and B. ischaemum. The rhizosphere soil microbial index was a good aggregative indicator of the general state of the microbial properties of the rhizospheres. The interactive effects of elevated CO2 and drought on plant growth and microbial properties significantly differed, indicating that elevated CO2 significantly alleviated the effects of drought stress on the microbial properties of the rhizosphere. In addition, the effects of elevated CO2 and drought on microbial biomass and enzymatic activities considerably varied between the two selected species. M. sativa generally experienced a better ameliorative effect than B. ischaemum.</p

Integration of transport concepts for risk assessment of pesticide erosion

Environmental contamination by agrochemicals has been a large problem for decades. Pesticides are transported in runoff and remain attached to eroded soil particles, posing a risk to water and soil quality and human health. We have developed a parsimonious integrative model of pesticide displacement by runoff and erosion that explicitly accounts for water infiltration, erosion, runoff, and pesticide transport and degradation in soil. The conceptual framework was based on broadly accepted assumptions such as the convection-dispersion equation and lognormal distributions of soil properties associated with transport, sorption, degradation, and erosion. To illustrate the concept, a few assumptions are made with regard to runoff in relatively flat agricultural fields: dispersion is ignored and erosion is modelled by a functional relationship. A sensitivity analysis indicated that the total mass of pesticide associated with soil eroded by water scouring increased with slope, rain intensity, and water field capacity of the soil. The mass of transported pesticide decreased as the micro-topography of the soil surface became more distinct. The timing of pesticide spraying and rate of degradation before erosion negatively affected the total amount of transported pesticide. The mechanisms involved in pesticide displacement, such as runoff, infiltration, soil erosion, and pesticide transport and decay in the topsoil, were all explicitly accounted for, so the mathematical complexity of their description can be high, depending on the situation