An a priori process for selecting candidate reference lakes for a national survey
20
Citation
29
Reference
10
Related Paper
Citation Trend
Abstract:
One of the biggest challenges when conducting a national-scale assessment of lakes, such as the 2007 US National Lake Assessment (NLA), is finding enough reference lakes to set appropriate expectations for the assessed sites. In the NLA, a random design was used to select lakes for sampling to make unbiased estimates of regional condition. However, such an approach was unlikely to yield enough minimally impacted lakes to use as reference sites, especially in disturbed regions. We developed a 3-stage process to select candidate reference lakes to augment the NLA probability sample in the northeastern USA (Northeast). Screening included a water-chemistry database filter, landuse evaluation, and analysis of aerial photographs. In the Northeast, we assembled a database of 2109 lakes >4 ha in surface area, of which 369 passed the water-chemistry screen. Of these, 220 failed the watershed landuse screen and 60 failed the aerial photograph screen, leaving a set of 89 optimal candidate reference lakes. Twenty of these lakes were sampled as potential reference lakes in the NLA. Based on a wide variety of indicators, NLA field measurements indicated that almost all (85–100%) of the chosen candidate reference lakes had least-disturbed water chemistry, although somewhat fewer had least disturbed physical habitat (74–79%) and biology (68–78%). Nevertheless, our 3-stage screening process was an efficient method for identification of good candidates for reference-lake sampling. The reference-lake selection process used in our study can be done in the office and relatively inexpensively. As such, it is very useful for large-scale regional or national studies encompassing areas too large to census. It also has the advantage of adding a level of consistency and quantification to the reference-site selection process.Keywords:
Reference data
Identification
Watershed area
Cite
Citations (13)
Watershed models typically are evaluated solely through comparison of in-stream water and nutrient fluxes with measured data using established performance criteria, whereas processes and responses within the interior of the watershed that govern these global fluxes often are neglected. Due to the large number of parameters at the disposal of these models, circumstances may arise in which excellent global results are achieved using inaccurate magnitudes of these "intra-watershed" responses. When used for scenario analysis, a given model hence may inaccurately predict the global, in-stream effect of implementing land-use practices at the interior of the watershed. In this study, data regarding internal watershed behavior are used to constrain parameter estimation to maintain realistic intra-watershed responses while also matching available in-stream monitoring data. The methodology is demonstrated for the Eagle Creek Watershed in central Indiana. Streamflow and nitrate (NO) loading are used as global in-stream comparisons, with two process responses, the annual mass of denitrification and the ratio of NO losses from subsurface and surface flow, used to constrain parameter estimation. Results show that imposing these constraints not only yields realistic internal watershed behavior but also provides good in-stream comparisons. Results further demonstrate that in the absence of incorporating intra-watershed constraints, evaluation of nutrient abatement strategies could be misleading, even though typical performance criteria are satisfied. Incorporating intra-watershed responses yields a watershed model that more accurately represents the observed behavior of the system and hence a tool that can be used with confidence in scenario evaluation.
Time of concentration
Watershed area
Watershed Management
Cite
Citations (70)
In this study, it aimed to present the necessity of watershed partnership by the regional management activity in the Sagami watershed. The expectation as a center group from the organization to watershed partnership is had from the watershed conference with the aspect of the watershed management. The watershed conference makes the best use of the feature as the organization, and the source region and the watershed of the role that cooperates the watershed and ties are large in the downstream region. The role that watershed partnership with the downstream region plays for the source region and the upstream region is large, and is necessary and indispensable in the future.
Watershed Management
Watershed area
Feature (linguistics)
Cite
Citations (0)
Abstract The Gajahwong watershed is part of the Opak watershed. The development of urban areas in the Opak watershed is very massive. The development of the urban regions in the Gajahwong watershed is the occurrence of land conversion from non-built land to built-up land. The land cover change will result in changes in the hydrological response of the watershed. The results showed that in the Gajahwong watershed, there was a decrease in agricultural land in the Gajahwong watershed, which was initially 30,209 km 2 in 2016, down to 20,204 km 2 in 2020. Agricultural land declines due to the conversion of functions to built-up land. Built-up land in the Gajahwong watershed increased by 4,483 km 2 . This condition resulted in an increase in the CN value in the Gajahwong watershed from the original in 2016 having a CN II of 73 and then increasing to 74. The results show that in 2016, the Gajahwong watershed had a peak discharge of 14.9 m 3 /s; in 2020, the peak discharge in the Gajahwong watershed decreased to 11.8 m 3 /s. The volume runoff in the Gajahwong watershed also reduced from 2880.21 mm in 2016 and then in 2020 to 2011,39 mm.
Time of concentration
Land Cover
Agricultural land
Watershed Management
Cite
Citations (0)
A two‐factor awareness‐appraisal model suggests that individuals' reactions to threatening circumstances are shaped by their awareness of the threat and their appraisal of the degree of threat the circumstances pose to them. This approach, applied to watershed conservation, predicts that individuals will be willing to clean up the rivers and streams of their watershed if they are familiar with local water features (rivers, streams, ponds, lakes) and if they consider these features of the watershed to be degraded. We tested the model by measuring watershed knowledge, appraisal of watershed quality, value assigned to protecting the watershed, and behavioral intentions regarding watershed preservation in a survey of 1,128 residents of two urban watersheds. The results supported the awareness‐appraisal model: Those residents who were aware of their watershed and considered it polluted expressed the strongest pro‐preservation behavioral intentions. These relationships were held in both watersheds, but were stronger for those who resided in the more degraded watershed .
Watershed Management
Cite
Citations (30)
Soil erosion and sediment control is important in watersheds with planned dam construction. For an efficient implementation of watershed management practices, identification of critical areas is vital. Many studies have made an effort to identify and prioritize critical sub-watersheds. But very limited studies have been conducted to rank sub-watersheds in terms of their sediment yield contribution at the watershed outlet. Therefore, the goal of this study is spatial priority of critical sources areas in Taleghan dam watershed based on three methods: (1) SSY-S: specific sediment yield at sub-watershed outlet (sediment yield/area), (2) SY-W: sub-watershed contribution to the sediment yield of the main watershed outlet/reservoir, and (3) SSY-W: specific sediment yield contribution of sub-watershed to the main watershed outlet/reservoir. The results of sub-watershed and prioritization showed that sub-watershed 22 has the highest sediment yield at its own sub-watershed outlet and main outlet of watershed. Also, implementing conservation practices in a high priority area shows a decrease in sediment yield at watershed outlet. However, sediment yield at outlet of watershed decreased about 11%, 15% and 17% from baseline scenario in methods 1, 2 and 3, respectively. The results show that the SSY-W method was more effective at reducing sediments entering the reservoir of Taleghan dam.
Watershed Management
Watershed area
Time of concentration
Cite
Citations (7)
This study was conducted to identify the runoff characteristics of non-point source according to rainfall in Dalseo and Daemyung watershed. Land-uses of the Dalseo and Daemyung watershed were surveyed to urban $72.1\%$ and mountainous $6.7\%$ , and urban $49.3\%$ and mountainous $20.5\%$ , respectively Mean runoff coefficients in each area were estimated to Dalseo watershed 0.49 and Daemyung watershed 0.16. In the relationship between the rainfall and peak-flow correlation coefficients(r) were determined to Dalseo watershed 0.9060 and Daemyung watershed 0.5620. In the relationship between the antecedent dry period and flrst flow runoff correlation coefficients(r) were determined to Dalseo watershed 0.7217 and Daemyung watershed 0.2464. In the relationship between the rainfall and watershed loading, exponent values of SS in Dalseo and Daemyung watershed were estimated to 0.54 and 0.496, respectively.
Time of concentration
Watershed area
Cite
Citations (4)
Watershed 변환은 수학적 형태학 분야로부터 나온 인기 있는 세분화 방법이다. 쌀, 밀, 옥수수는 전통적인 watershed 알고리듬에 의해 과세분화되어진다. 그러므로 이 논문은 확장된 최대 변환을 위해 이중 레벨의 임계치를 순간 유지하는 임계치값의 자동 선택에 의해 향상된 watershed 세분화 알고리듬을 제안한다. 첫 번째로 변형된 거리 영상은 자동 선택된 임계치를 위해 이중 레벨의 임계치를 순간 유지하여 진행되어 진다. 선택된 임계치는 확장된 최대 변환을 위해 사용되고 watershed 변환은 마무리 된다. watershed 등선 라인은 원 이진영상으로 중첩되어진다. 실험적 결과는 이런 진행과정들은 더 크게 확장하여 과세분화된 문제점을 해결 하는 것을 보인다.
Cite
Citations (5)
The quality of surface and ground water resources is deteriorating with time due to numerous natural and anthropogenic sources of pollution. As surface and ground water is major source of drinking water in rural area in the study area, made essential to monitor its quality regularly. Water Quality Index (WQI) show a significant role and a useful tool for evaluating the overall quality of water aimed for drinking purpose. This method converts the complex and large data on water quality trends to a single value which can be easily understandable to the common public, local governing bodies and policymakers. In the present research work an attempt was made to check suitability of surface and ground water for drinking purpose using Water Quality Index method. The water quality was estimated by analyzing selected physico-chemical parameters which play significant role in determining water quality such as pH, Alkalinity, Electrical Conductivity, Fluoride, Chloride, Nitrate, Sulphate, Potassium, Total Hardness, E. Coli, Turbidity, Total Dissolved Solids, Dissolved Oxygen and Biochemical Oxygen Demand. Total 32 surface and 35 ground water samples were collected from different selected locations in the study area during pre and post-monsoon seasons respectively. The overall results revealed that almost all the surface water sources from the Bhokardan area, Jalna District, India was found unsuitable for drinking purposes. The application of WQI method to evaluate sequential variations in surface as well as ground water quality was therefore found suitable and effective tool for monitoring and proper management of drinking water resources.
Turbidity
Alkalinity
Total dissolved solids
Biochemical oxygen demand
Cite
Citations (0)
The watershed characteristics were analyzed based on DEM and HEC for the major processes of lowland water infilling,calculation of water flow direction,water flow accumulation,and water network layout,finally the digital basin was generated.The Chunhua watershed in Jiangning,southern Jiangsu,was taken as a case study using the new tool set.The results of the study show:the watershed boundary line is almost identical to the ridge line in the mountain areas that are less impacted by human,but the result is much different from the actual watershed in the flat areas or areas that are much impacted by human.The watershed boundary line needs to be revised artificially further.In view of efficiency and precision,it is viable to use this new tool to extract watershed characteristics.
Time of concentration
Boundary line
Cite
Citations (1)