Suitability of Watershed Models to Predict Distributed Hydrologic Response in the Awramba Watershed in Lake Tana Basin

Planning effective landscape interventions is an important tool to fight against land degradation and requires knowledge on spatial distribution of runoff. The objective of this paper was to test models that predict temporal and spatial distribution of runoff. The selected models were parameter‐efficient semi‐distributed watershed model (PED‐WM), Hydrologiska Byrans Vattenbalansavdelning integrated hydrological modeling system (HBV‐IHMS), and Soil and Water Assessment Tool (SWAT). We choose 7‐km² Awramba watershed in the Lake Tana basin with detailed hydrological information for testing these models. Discharge at the outlet, rainfall, and distributed information on infiltration rates, water table, and extent of the saturated area were collected from 2013 to 2015. The maximum saturated area was 6·5% of the watershed. Infiltration rates exceeded rainfall intensities 91% of the time. Hence, saturation excess runoff was the main runoff mechanism. Models were calibrated for the rainy seasons in 2013 and 2014 and validated for 2015. For daily flow validation, the PED‐WM model (Nash–Sutcliff efficiency, NSE = 0·61) outperformed HBV‐IHMS (NSE = 0·51) and SWAT (NSE = 0·48). Performance on monthly time step was similar. Difference in model behavior depended on runoff mechanism. In PED‐WM, saturation excess is the main direct runoff process and could predict the maximum extent of the saturated area closely at 6·9%. HBV‐IHMS model runoff simulation depended on soil moisture status and evapotranspiration, and hence was able to simulate saturation excess flow but not the extent of the saturated area. SWAT, where infiltration excess is the main runoff mechanism, could only predict the monthly discharges well. This study shows that prevailing runoff mechanisms and distribution of runoff source areas should be used for proper model selection. Copyright © 2016 John Wiley & Sons, Ltd.     

Model Assessment of Cattle and Climate Impacts on Stream Fecal Coliform Pollution in the Salmon River Watershed, British Columbia, Canada

A bacterial water quality model (BWQM) was developed and used to evaluate the impacts of cattle farming and climate change on the stream fecal coliform pollution in the Salmon River watershed in south-central British Columbia, Canada. The accuracy of the model simulation was evaluated using the Nash-Sutcliffe coefficient of efficiency (COE). The BWQM simulated the observed field data well, with the values of the COE ranging from 0.76 to 0.78 for the stream flow, from 0.55 to 0.60 for the fecal coliform (FC) concentration, and from 0.85 to 0.89 for the FC loading. The BWQM captured more than 79%, 66%, and 90% variation of the daily stream flow, FC concentration, and FC loading, respectively. The BWQM predicts that between 70% and 80% of the FC were transferred from the cattle farm to the Salmon River through the snowmelt-caused surface runoff during late winter and early spring, with the balance 20% to 30% coming from the soil-lateral flow and the groundwater return flow. The model also indicates that the stream FC concentration is sensitive to the distance of the cattle farm to the Salmon River. The model scenario analysis reveals that the climate change, at an assumed 1??C increment of daily air temperature, results in an increase in the stream FC concentration in the spring, fall, and winter, but there is also a decrease in the summer. The increased air temperature also changes the seasonal pattern of the stream FC concentration. Rainfall can reduce the stream FC concentration and mitigate the impact of the increased air temperature on the stream FC concentration as long as it does not result in a surface runoff or flooding event.     

Farm Nutrient Management Practices in Two Geographically Diverse Watersheds in the Cottonwood River Watershed of Minnesota, USA

The characteristics of a river are shaped by the quality of the tributaries that flow into it and each of the tributaries in turn reflects the management practices that occur on the soils and landscapes in their drainage areas. In the Cottonwood River of Minnesota, USA and many of its tributaries, nutrient enrichment [primarily nitrogen (N) and phosphorus (P)] and suspended sediments contribute to nonpoint source pollution. Our objective was to assess farm characteristics and nutrient management practices among producer/operators in two southwestern Minnesota watersheds, and relate these characteristics to soil and landscape differences as reflected by agroecoregions. Producer/operators were interviewed in a face-to-face interview during summer 2002 about agricultural production management practices in two tributaries of the Cottonwood River. The Sleepy Eye Creek watershed (SECW) is located in gently rolling to flat soils formed in glacial till. The Highwater-Dutch Charley Creek watershed (HDCCW) is located in moderately steep, 2–6% slope, soils formed in glacial moraine. Nitrogen and P rates applied to corn were significantly greater in the SECW than the HDCCW, and more of the N was applied in the fall in the SECW than in the HDCCW, where more was applied in spring. More farmers tested soil for plant available P in the SECW than in the HDCCW. Results from both watershed indicated that forty-seven (29%) fields with soil test phosphorus records exceeded 25 ppm (Bray 1) or 20 ppm (Olsen). Nineteen (7.4%) fields received applications of both manure and N fertilizer, and 13 (5.1%) fields received applications of both manure and phosphate (P) fertilizer. Nitrogen and P application rates ranged from 234 to 315 kg N ha^?1 and 134 to 168 kg P₂O₅ ha^?1 for fields receiving both manure and fertilizer. Strategies for improving nutrient management practices in these two watershed areas should take into consideration soil and landscape differences that influence which nutrient management practices are most risky and which are most likely to improve water quality.     

An Integrated Modeling Approach to Total Watershed Management: Water Quality and Watershed Assessment of Cheney Reservoir, Kansas, USA

Degradation of water quality is the major health concern for lakes and reservoirs in the central regions of the United States as a result of heavily devoted agricultural production. A vital key to the development of a reservoir management strategy is to identify nutrient loading that describes associated water quality conditions in reservoirs. This study integrated AnnAGNPS watershed and BATHTUB lake models to simulate actual lake water quality conditions of Cheney Reservoir, KS, and demonstrated the use of the coupled model for simulating lake response to changes in different watershed land use and management scenarios. The calibrated current-conditions model simulated in-lake reductions as much as 52% for TN, 48% for TP, and 70% for chlorophyll a due to conversion to native grass, and increases as much as 4% for TN, 9% for TP and 6% for chlorophyll a due to conversion of land from the Conservation Reserve Program (CRP) to cropland (15.5% of watershed). This model also demonstrated an increase in chlorophyll a (19%) as the lake sediment capacity was reached over the next century.     

柴汶河流域水土保持规划经济效益分析

该文对流域综合治理规划中各项措施所获取的林木产品效益、农业生产效益、减沙保土效益、水源涵养方面的效益、渔业生产效益进行了综合分析计算, 得出规划治理的各项措施的综合效益。并用经济分析的理论进行了经济效益分析, 从静态、动态、灵敏度3个方面进行经济指标计算, 得出该治理规划经济效益高、风险小、规划可行的结论。从而对规划进行了验证, 提高了规划的科学性。     

汤峪河流域径流小区水土保持监测点2017—2019年监测结果分析

汤峪河流域径流小区水土保持监测点主要对气象因子(降水)、径流泥沙、田间管理、土壤含水量和植被覆盖度/郁闭度等进行监测,监测数据能反映宁南陇东丘陵沟壑区的典型特征.在监测点选择5个相同坡度不同治理措施的标准径流小区——人工草、灌乔混交、灌木、乔木和裸地小区,对治理前后小区径流深、径流系数、土壤流失量、雨前土壤含水量和雨后...     

Dynamics of Soil Organic Carbon Storage and Erosion due to Land Use Change (Illinois,USA)

Eurasian Soil Science - Many factors including land use, management history, soil series, climate, and soil landscape processes affect the dynamics of soil organic carbon (SOC). The primary...     

Grizzly bear response to human development and activities in the Bow River Watershed, Alberta, Canada

Few studies have reported the effects of multiple human activities on grizzly bears, Ursus arctos. We document the degree of grizzly bear response to various human developments as a function of multiple interacting variables based on observed median distances to roads, trails and development features in a landscape where human presence is widespread. Female grizzly bears remained further than males from paved roads regardless of habitat quality or time of day. Males were found closer to paved roads when within or adjacent to high quality habitat and during the period of least human activity. The combination of traffic volume and highway configuration, however, overrides a bear’s attraction to high quality habitats for high-speed, high-volume, highways. Avoidance of busy transportation corridors was strongest in the adult segment of the population. Bears were found closer to trails during the human inactive period when within high quality habitat and further from trails when distant to high quality habitat. Our data indicated an inverse relationship between the sexes in response to vehicles and traffic noise compared to the response to human settlement and encountering people. Female bears were found further away than males in relation to vehicles and traffic noise, yet found closer than males to human settlement and places where people may be encountered. Those males that were more willing to exploit high quality habitat near roads, did so at night and where hiding cover was present. Adult females were the most risk-averse cohort, choosing to avoid humans instead of seeking out high quality habitats. Adult female grizzly bears were influenced most by human activities and development. Management agencies must maintain access to high quality habitat, especially for adult females, and create new opportunities to support the reproductive potential of the population.     

Nature and Magnitude of Atmospheric Fluxes of Total Inorganic Nitrogen and Other Inorganic Species to the Tampa Bay Watershed, FL, USA

We estimated the total inorganic fluxes of nitrogen (N), sulfur (S), chloride (Cl^?, sodium (Na⁺, calcium (Ca²⁺, magnesium (Mg²⁺, potassium (K⁺ and hydronium (H⁺. The resistance deposition algorithm that is programmed as part of the CALMET/CALPUFF modeling system was used to generate spatially-distributed deposition velocities, which were then combined with measurements of urban and rural concentrations of gas and particle species to obtain dry deposition rates. Wet deposition rates for each species were determined from rainfall concentrations and amounts available from the National Acid Deposition Program (NADP) monitoring network databases. The estimated total inorganic nitrogen deposition to the Tampa Bay watershed (excluding Tampa Bay) was 17 kg-N ha^?1 yr^?1 or 9,700 metric tons yr^?1, and the ratio of dry to wet deposition rates was ～2.3 for inorganic nitrogen. The largest contributors to the total N flux were ammonia (NH₃ and nitrogen oxides (NO _x at 4.6 kg-N ha^?1 yr^?1 and 5.1 kg-N ha^?1 yr^?1, respectively. Averaged wet deposition rates were 2.3 and 2.7 kg-N ha^?1 yr^?1 for NH₄ ⁺ and NO₃ ^?, respectively.     

Changes in the concentrations and speciation of aluminum in response to an experimental addition of ammonium sulfate to the bear Brook Watershed,Maine, USA

An understanding of the biogeochemistry of aluminum (Al) in acid-sensitive terrestrial and aquatic ecosystems is critical to assessments of the effects of acidic deposition. Bear Brook Watershed, Maine, USA includes paired watersheds, East Bear and West Bear. Starting in November 1989, experimental additions of ammonium sulfate ((NH₄)₂SO₄; 900 mol/ha-yr) have been made to West Bear Brook Watershed. Chemical analysis of soil and stream waters were conducted to evaluate the speciation of Al prior to (1987–89) and following (1989–92) the experimental treatments. Before the treatments, soilwater Al occurred largely as inorganic monomeric Al (Ali). Concentrations of organic monomeric Al (Alo), Ali and dissolved organic C (DOC) were high in soil solutions draining the E horizon, and decreased in the lower mineral soilwater (Bs horizon) and streamwater. Streamwater concentrations of monomeric Al (Alm) were largely in the form of Alo. After the (NH₄)₂SO₄ treatments were initiated in the West Bear Brook Watershed, concentrations of Alm increased in soilwater and streamwater, largely as Ali. These increases in Al accompanied decreases in pH and increases in concentrations of SO₄ ^2? and NO₃ ^? in drainage waters. Increases in stream concentrations of Al were particularly evident during high flow events. This pattern, coupled with the increases in concentrations of Ali in upper soilwaters in response to the (NH₄)₂SO₄ addition, suggests that episodic increases in Ali were due to inputs of water entering the stream from shallow hydrologic flowpaths.     

新疆头屯河流域侵蚀产沙特征

依据流域内降雨及水泥沙资料，对新疆头屯河流域侵蚀产沙特征进行了系统分析。结果结果表明：头屯河流域侵蚀产沙类型较为复杂，主要侵蚀类型有水蚀、风蚀、重力侵蚀及人类不合理的社会经济活动所引起的人为加速侵蚀，尤以水力侵蚀为主。该流域水蚀的特征是冰川融雪水侵蚀的存在，流域蚀产沙具有明显的时空分异特征。在空间上具有明显的垂直分异规律，海拔为８００￣１４００ｍ，植被较差，是该流域主要产沙区，在时间上亦表现出相     

Development and Assessment of Neural Network and Multiple Regression Models in Order to Predict PM10 Levels in a Medium-sized Mediterranean City

Suspended particulate matter is significantly related to the degradation of air quality in urban agglomerations, generating adverse health effects. Therefore, the ability to make accurate predictions of particulate ambient concentrations is important in order to improve public awareness and air quality management. This study aims at developing models using multiple regression and neural network (NN) methods that might produce accurate 24-h predictions of daily average (DA) value of PM10 concentration and at comparatively assessing the above mentioned techniques. Pollution and meteorological data were collected in the urban area of Volos, a medium-sized coastal city in central Greece, whose population and industrialization is continuously increasing. Both models utilize five variables as inputs, which incorporate meteorology (difference between daily maximum and minimum hourly value of ground temperature and DA value of wind speed), persistency in PM10 levels and weekly and annual variation of PM10 concentration. The validation of the models revealed that NN model showed slightly better skills in forecasting PM10 concentrations, as the regression and the NN model can forecast 55 and 61% of the variance of the data, respectively. In addition, several statistical indexes were calculated in order to verify the quality and reliability of the developed models. The results showed that their skill scores are satisfying, presenting minor differences. It was also found that both are capable of predicting the exceedances of the limit value of 50 μg/m³ at a satisfactory level.     

Friction velocity and aerodynamic roughness of conventional and undercutter tillage within the Columbia Plateau, USA

Friction velocity (u_*) and aerodynamic roughness (z_o) at the soil–plant–atmosphere interface affect wind erosion, but no attempts have been made to quantify these parameters as affected by tillage systems within the Columbia Plateau region of the Pacific Northwest United States. Wind velocity profiles above adjacent field plots (>2 ha), with plots subject to conventional or undercutter tillage during the summer fallow phase of a winter wheat–summer fallow rotation, were measured over 50 high wind events (wind velocities in excess of 6.4 m s⁻¹ at a height of 3 m) during 2005 and 2006 near Lind, Washington to determine u_* and z_o of tillage treatments. Wheat stubble plots were subject to either conventional (disks) or undercutter (wide V-shaped blades) tillage in spring and then periodically rodweeded prior to sowing winter wheat in late summer. Prior to sowing, u_* for conventional and undercutter tillage respectively averaged 0.36 and 0.46 m s⁻¹ in 2005 and 0.38 and 0.40 m s⁻¹ in 2006 while z_o for conventional and undercutter tillage respectively averaged 2 and 7 mm in 2005 and 2 and 4 mm in 2006. The aerodynamically rougher surface of undercutter tillage was predicted to suppress vertical dust flux; this was collaborated with observations in the field where undercutter tillage reduced dust flux as compared with conventional disk tillage. Undercutter tillage, therefore, appears to be an effective management practice to roughen the surface and thereby suppress dust emissions from agricultural land subject to summer fallow within the Columbia Plateau.     

大坪子小流域综合治理为“长治”工程添彩

云南省会泽县五星乡大坪子小流域是"长治"七期工程云南省干河项目区(会泽县)实施的10条小流域之一,于2005年12月开工建设,2006年12月全面完成治理任务。经过1年的治理,年均土壤侵蚀模数由3206t/km2降为1539t/km2,年土壤侵蚀总量由4.54万t降为2.18万t,不仅治理了水土流失,而且促进了产业结构调整,奠定了该流域生态立体开发基础。介绍了该流域"一事一议"筹措资金,建立工程回访制,并实行"五转变、五结合"、"五统一、四集中"的工作思路和工作方式。     

青海湟水河流域不同退耕还林模式水土保持效应

基于野外定点观测资料收集和室内实验分析,研究了青海湟水河流域不同退耕还林模式下水土保持效应,结果表明:41 a青杨>41 a云杉>天然次生灌木林>9 a云杉沙棘混交>9 a沙棘>9 a云杉(坡位下)>9 a云杉(坡位上)>4 a云杉沙棘混交>农田.同时对照农耕地土壤:退耕还林地土壤理化性质和生物特性在退耕5 a后有明显变化,天然次生灌木林稳渗率>9 a云杉沙棘混交>4 a云杉沙棘混交>农田;土壤可蚀性因子从农耕地的0.773减少到次生灌木林的0.483;41 a青杨枯落物单位面积有效蓄水量是41 a云杉的2.6倍.     

浅谈小流域综合治理规划的内容和程序

通过对小流域水土资源进行分析和评价, 对小流域的土地利用、农林牧副各业进行规划, 是小流域综合治理的指导。其目的是确定小流域的生产发展方向, 以防治水土流失, 保护、改良和合理利用水土资源, 提高土地生产力, 充分发挥小流域的经济效益和生态效益, 建立一个人工控制的、合理、稳定的生态经济系统。     

汉江小流域土壤氮素空间分布特征及影响因素

氮素是土壤中不可或缺的营养元素之一,对植物生长具有至关重要的作用。利用网格采样法(30m×30m)和典型样地取样法在汉江余姐河小流域进行土样采集,每个样点分为3层A1(0—20cm),A2(20—40cm),A3(40—60cm),分别测定其土壤全氮、土壤铵态氮和土壤硝态氮含量。研究了土壤氮素的空间异质性、氮素的组成比例以及不同土地利用类型下土壤全氮、铵态氮和硝态氮与环境因子间的相关关系,并且分析了不同形态氮素间的相互关系。结果表明:土壤氮素的空间变异性为土壤硝态氮土壤铵态氮土壤全氮;土壤全氮与硝态氮在A1土层为强空间相关性,在A2,A3层为中等程度的空间相关性,土壤铵态氮在各土层均表现为中等空间相关性;农地、林地、草地对全氮储量的贡献依次增大;相较于林地草地,农地对铵态氮储量的贡献最大;而草地对硝态氮储量的贡献在三种土地利用中最大;不同土地利用类型中,农地的氮素空间分布主要与土壤粒径具有相关性,而与地形因子(坡度、坡向等)相关性较小;林地的氮素空间分布主要与地形因子相关性较高,草地介于两者之间;在流域内增加草地林地面积,在流域出口处布设林草地等措施可以减少流域土壤氮素的流失。     

Mercury Contamination of Alluvial Sediments within the Essequibo and Mazaruni River Basins,Guyana

Small- and medium-scale mining operations in Guyana have increased significantly since the late 1980s. The majority of these gold mining operations utilize mercury (Hg) amalgamation methods in the recovery process, raising the question as to the significance of Hg inputs to the environment from mining activities. In March and April, 2001, 168 samples were collected from floodplain, sand bar, and channel bed deposits along a 350 km reach of the Mazaruni River and a 160 km reach of the Essequibo River. Distinct trends in the geochemical data suggest that much of the Hg found in the alluvial deposits is related to anthropogenic sources, including (1) Hg concentrations in floodplain, channel bed and sand bar deposits locally exceed background values defined by ferralitic soils; (2) core data reveal that Hg concentrations within floodplain deposits have increased in recent years; and (3) high Hg concentrations along the channels can be attributed to the influx of material from tributaries affected by mining operations, or to mining activities along the rivers. Recent investigations in Amazonia have argued that Hg from amalgamation mining represents a small portion of the total Hg load to riverine systems, the majority coming from the erosion of Hg enriched upland soils within deforested terrain. Geochemical data from the Essequibo and Mazaruni Rivers suggest that Hg from mining may be a more significant source in Guyana where large-scale deforestation is limited. However, it is unclear whether the increased Hg represents the direct input associated with the amalgamation process, or Hg associated with the erosion of soils and sediments that results from activities that accompany mining.     

Long-Term Hydrological Impacts of Land Use/Land Cover Change From 1984 to 2010 in the Little River Watershed,Tennessee

Assessing long-term hydrological impacts of land use/land cover (LULC) change is of critical importance for land use planning and water resource management. The Little River Watershed, Tennessee, is an important watershed supporting drinking water and recreational activities within and around the Great Smoky Mountains National Park in the Unites States. However, the potential hydrological impacts of LULC change, especially urbanization in recent decades, are not quantified. This paper assessed the long-term impacts of LULC change on streamflow and non-point source pollution using the Soil and Water Assessment Tool (SWAT) and a detailed LULC record from 1984 to 2010. The SWAT was first calibrated and validated using observed streamflowin 2010 and then simulated using different LULC patterns in 1984-2010 to quantify the long-term hydrological impacts caused by the LULC change. Simulated results indicated a minor 3% increase in streamflow for the whole watershed from 1984 to 2010, but with a distinct spatial pattern. The increase in streamflow is closely related to urban development. Almost no streamflow increase occurred in the upper watershed within the national park, whereas > 10% increase occurred in the lower watershed, especially in areas close to cities. Model simulation also suggested 34.6% reduction in sediment and about 10% reduction in nutrient loads from 1984 to 2010, closely related to the decrease in agricultural land. However, without calibration and validation, the simulated reduction in the sediment and nutrient loads may be problematic because SWAT mainly simulates the static LULC patterns, whereas LULC transitions, such as construction phases, may generate more sediment and nutrient loads. In addition, the simulation also did not account for the sediment and nutrients generated from stream bank erosion.     

重庆笋溪河流域河岸带水体-土壤-植物的氮磷特征及影响因素

为明晰重庆笋溪河流域河岸带水体、土壤和植物的氮磷特征及其影响因素,采用描述性统计、聚类分析、相关分析和冗余分析的方法,探讨三峡库尾小流域河岸带水体、土壤和植物的氮、磷含量特征、空间分布和各圈层氮磷的相关性及水体氮磷的影响因素.结果表明:(1)河岸带受河流区段影响,从上游到下游,水体氮磷与土壤全氮的含量先减小后增大,下游...