Equivalence of Rainfall Type and Maximum Discharge to the Drainage Channel Capacity

This research will identify the equivalence of the serial rainfall to the design flood. The equivalence of serial rainfall data is very necessary to solve the flooding problem. A case study is in the University of Brawijaya-Malang-East Java Province-Indonesia. The methodology consists of analyzing the design flood using the Nakayasu Synthetic Unit Hydrograph and then analyzing the equivalence of cumulative serial rainfall to the design flood. The equivalence of rainfall in this research discusses two items: the rainfall equivalence to the hydraulic and hydrologic conditions. Based on the hydraulic condition, the capacity of the drainage channel can store the rainfall for 85.77 mm for the return period of 2 years; 105.86 mm for the return period of 5 years; and 119.26 mm for the return period of 10 years. However, based on the hydrologic condition, for the design flood with the return period of 2 years is 382.25 m3/s, and it has the equivalence close to the discharged recording of AWLR Gadang that is 386.76 m3/s which is due to the rainfall for 11 mm (the category of heavy rain); for the return period of 5 years, the design flood is 471.07 m3/s, and it is equivalent with the flood discharge of 463.73 m3/s that is caused by the rainfall of 12.1 mm (the category of heavy rain); for the return period of 10 years, the design flood is 589.99 m3/s, and it is caused by the rainfall of 13.4 mm (the category of heavy rain). Based on the hydraulic and hydrologic condition, the capacity of the drainage channel that is installed in the campus region of Brawijaya University, it can be concluded that for the return period of 2 years, the drainage channel is only able to reduce 41% of flood volume; for the return period of 5 years, the drainage channel is only able to reduce 26% of flood volume; however, for the return period of 10 years, the drainage channel is only able to reduce 23% of flood volume.

Effect of precipitation and stream discharge on the source composition of stream water

<p>The exchange of water between streams and groundwater plays an important role for hydrologic and biogeochemical processes. Along a stream the composition of stream water is modified by sequential losses of stream water with the current in-stream chemical signature to the subsurface and gains of water with another signature from the subsurface. This process has been termed hydrologic turnover. To date, most studies on hydrologic turnover have been focused on small stream networks. Moreover, the influence of hydrologic conditions on hydrologic turnover has not been systematically investigated. Taking the lower Selke River in central Germany as an example, we evaluated the evolution of stream-groundwater exchange and the source composition of stream water under different precipitation and stream discharge conditions, based on a coupled stream-groundwater model built in MODFLOW using the Streamflow-routing (SFR1) package. The results show that the stream reaches could be classified into three types: permanently gaining reaches, permanently losing reaches, and transitional reaches. Transitional reaches range from losing condition at higher stream discharge or lower precipitation to gaining condition at lower stream discharge or higher precipitation. In the lower Selke River with a length of 30 km, transitional reaches account for nearly 30% of the total river length in the studied period from 2011 to 2018. Regardless of dry or wet hydrologic condition, nearly 80% of the total groundwater contribution to stream discharge at the catchment outlet were generated over 20% of the total river length. This indicates diffuse groundwater pollution such as from agricultural nitrate may enter the stream network predominantly at a few distinct reaches. Our analysis can help to prioritize areas in a catchment where reduction of diffuse groundwater pollution would have the highest impact on improving stream water quality.</p>

Conservation–Protection of Forests for Wildlife in the Mississippi Alluvial Valley

The nearly ubiquitous bottomland hardwood forests that historically dominated the Mississippi Alluvial Valley have been greatly reduced in area. In addition, changes in hydrology and forest management have altered the structure and composition of the remaining forests. To ameliorate the detrimental impact of these changes on silvicolous wildlife, conservation plans have emphasized restoration and reforestation to increase the area of interior (core) forest habitat, while presuming negligible loss of extant forest in this ecoregion. We assessed the conservation–protection status of land within the Mississippi Alluvial Valley because without protection, existing forests are subject to conversion to other uses. We found that only 10% of total land area was currently protected, although 28% of extant forest was in the current conservation estate. For forest patches, we prioritized their need for additional conservation–protection based on benefits to forest bird conservation afforded by forest patch area, geographic location, and hydrologic condition. Based on these criteria, we found that 4712 forest patches warranted conservation–protection, but only 109 of these forest patches met our desired conservation threshold of >2000 ha of core forest that was >250 m from an edge. Overall, 35% of the area of forest patches warranting conservation–protection was protected within the conservation estate. Even so, for those forest patches identified as most in need of conservation–protection, less than 10% of their area was currently protected. The conservation–protection priorities described fill an unmet need for land trusts and other conservation partners pursuing strategic forest protection in support of established bird conservation objectives.

Multi-Criteria Evaluation for China Low-Impact Development Based on Principal Component Analysis

Multiple benefit evaluation may become complicated due to varied and unquantifiable indicators. This study presents a multicriteria approach to evaluate Low Impact Development (LID) performance through an aggregation of principal component analysis and correlation analysis (PCCA). The approach is based on the rule of triple bottom line and complies with the China-specific planning land-use type and site-specific hydrologic and hydrologic condition. The quantitative indicators are coupled with the Stormwater Management Model (SWMM) software and filed investigation; the qualitative indicators are valued by a numerical unit system that converts the level of importance to numbers 5, 4, 3, 2 and 1. The results indicate that the PCCA approach could evaluate the LID performance with fewer dimensions of variables based on environmental, economic and social concerns comprehensively. The principal components concentrated on three streams: (1) runoff quantity and quality control; (2) minimize cost and improve robustness; and (3) improve system management and aesthetic enhancement. Taken together, these streams match the objective of sponge city construction with LID techniques. The PCCA approach is a multicriteria decision-aid tool that helps the decision maker choose the appropriate LID technique.

Situating Urban Drought Resilience

Cities around the world are experiencing greater water stress as the result of growing urban populations, increasing per capita wealth (and water use), and climate change. This chapter examines the concept urban drought resilience. The central hypothesis of this chapter is that the resilience of cites to future droughts can be understood based on socio-ecological characteristics, including biophysical, economic, and social factors. I hypothesize that resilience to urban drought can be predicted by the antecedent hydrologic condition, the polycentric aspects of governance, and the capacity of governance, both to provide feedback for adaptation and to respond. I propose a research agenda to understand urban drought resilience and to create tools that cities can use to increase this resilience. Among these are actionable metrics of urban drought resilience, analogous to widely used economic metrics used by governments to manage economic conditions, including metrics of equity as well as system-level metrics of hydrologic condition.

Carbon pool trends and dynamics within a subtropical peatland during long-term restoration

BackgroundThe Florida Everglades has undergone significant ecological change spanning the continuum of disturbance to restoration. While the restoration effort is not complete and the ecosystem continues to experience short duration perturbations, a better understanding of long-term C dynamics of the Everglades is needed to facilitate new restoration efforts. This study evaluated temporal trends of different aquatic carbon (C) pools of the northern Everglades Protection Area over a 20-year period to gauge historic C cycling patterns. Dissolved inorganic C (DIC), dissolved organic C (DOC), particulate organic C (POC), and surface water carbon dioxide (pCO2(aq)) were investigated between May 1, 1994 and April 30, 2015.ResultsAnnual mean concentrations of DIC, DOC, POC, and pCO2(aq)significantly decreased through time or remained constant across the Water Conservation Areas (WCAs). Overall, the magnitude of the different C pools in the water column significantly differed between regions. Outgassing of CO2was dynamic across the Everglades ranging from 420 to 2001 kg CO2yr-1. Overall the historic trend in CO2flux from the marsh declined across our study area while pCO2(aq)largely remained somewhat constant with the exception of Water Conservation Area 2 which experienced significant declines in pCO2(aq). Particulate OC concentrations were consistent between WCAs, but a significantly decreasing trend in annual POC concentrations were observed.ConclusionsHydrologic condition and nutrient inputs significantly influenced the balance, speciation, and flux of C pools across WCAs suggesting a subsidy-stress response in C dynamics relative to landscape scale responses in nutrient availability. The interplay between nutrient inputs and hydrologic condition exert a driving force on the balance between DIC and DOC production via the metabolism of organic matter which forms the base of the aquatic foodweb. Along the restoration trajectory as water quality and hydrology continues to improve it is expected that C pools will respond accordingly.

A study of the relationship between wetland vegetation communities and water regimes using a combined remote sensing and hydraulic modeling approach

Hydrologic condition is a major driving force for wetland ecosystems. The influence of water regimes on vegetation distribution is of growing interest as wetlands are increasingly disturbed by climate change and intensive human activities. However, at large spatial scales, the linkage between water regimes and vegetation distribution remains poorly understood. In this study, vegetation communities in Poyang Lake wetland were classified from remote sensing imagery. Water regimes characterized by inundation duration (IDU), inundation depth (IDE), and inundation frequency were simulated using physics-based hydraulic models and were then linked with vegetation communities by a Gaussian regression model. The results showed that the Carex community was found to favor more hydrologic environments with longer IDU and deeper IDE in comparison to the Phragmites community. In addition, we found that the Carex community could survive in a relatively wider variety of hydrological conditions than the Phragmites community. For the typical sub-wetlands of the Poyang Lake National Nature Reserve (PLNNR), only the influence of IDU on the distribution of vegetation communities was significant. Outcomes of this research extend our knowledge of the dependence of wetland vegetation on hydrological conditions at larger spatial scales. The results provide practical information for ecosystem management.

A Preliminary Research on the Mechanism of Trench Landslide - Exemplified by Hejiacao Landslide in Zhen’an County of Shangluo

Through the detailed investigation of Hejiacao landslide in Zhen'an county, this paper analysed the developing features and forming factors of the trench landslides, Meanwhile, it preliminarily discusses the mechanism of deformation and failures for the trench landslide. The investigation shows that: 1The trench landslide is special in shape, mainly in pushing type with low angle, and has characters of slow creep speed and long time. It mainly takes place in populated regions with serious damage; 2The trench landslide is controlled by many factors, such as trench terrain, poor lithology, hydrologic condition and human activities; 3The trench landslide experiences three phases: Deposition-crack, pushing-creep and final destruction in the process of forming and movement.

Nutrient-based ecological consideration of a temporary river catchment affected by a reservoir operation to facilitate efficient management

The water quality status of the Kouris river in Cyprus was examined in order to fulfil the requirements for ecological quality as defined by the Water Framework Directive-2000/60/EC. Nitrate concentration (mean value) was increased in the Limnatis (2.8 mg L−1) tributary in comparison with the Kryos (2.1 mg L−1) and Kouris (1.0 mg L−1) tributaries depicting the influence of anthropogenic activities. The total maximum daily nutrients loads (TMDLs) based on the flow duration curves approach, showed that nutrients loads exceeded threshold values (33.3–75.6% in all hydrologic condition classes in the Kouris tributary, and 65–78% in the Limnatis tributary) especially under low flow conditions. The TMDL graph is intended to guide the temporal schedule for chemical sampling in all hydrologic classes. Kouris reservoir is an oligotrophic system, strongly influenced by the river’s flash-flood character but also by the implemented management practices. Kouris river outflow, which was reduced to one-tenth in the post dam period altered the wetland hydrologic network and contributed to the decrease of aquifer thickness. Continuous evaluation and update of the River Basin Management Plans will be the basis for the sustainable development of the Kouris basin.

Soil, snow, weather, and sub-surface storage data from a mountain catchment in the rain–snow transition zone

A comprehensive hydroclimatic data set is presented for the 2011 water year to improve understanding of hydrologic processes in the rain-snow transition zone. This type of dataset is extremely rare in scientific literature because of the quality and quantity of soil depth, soil texture, soil moisture, and soil temperature data. Standard meteorological and snow cover data for the entire 2011 water year are included, which include several rain-on-snow events. Surface soil textures and soil depths from 57 points are presented as well as soil texture profiles from 14 points. Meteorological data include continuous hourly shielded, unshielded, and wind corrected precipitation, wind speed, air temperature, relative humidity, dew point temperature, and incoming solar and thermal radiation data. Sub-surface data included are hourly soil moisture data from multiple depths from 7 soil profiles within the catchment, and soil temperatures from multiple depths from 2 soil profiles. Hydrologic response data include hourly stream discharge from the catchment outlet weir, continuous snow depths from one location, intermittent snow depths from 5 locations, and snow depth and density data from ten weekly snow surveys. Though it represents only a single water year, the presentation of both above and below ground hydrologic condition makes it one of the most detailed and complete hydro-climatic datasets from the climatically sensitive rain-snow transition zone for a wide range of modeling and descriptive studies. Data are available at doi:10.1594/PANGAEA.819837.