Simulating regional full-chain water balance using a novel surface water-groundwater coupled model

The goal of this study is to define the role of lakes in the energy and water cycling of the lake-rich central Mackenzie River Basin and discuss the impacts of climate variability on the regional terrestrial water balance. This is pursued by synthesizing the results of measured data on a regional scale. Our results indicate that lake-rich regions are high energy landscapes in the thaw season. Lakes have larger net radiation and much larger water vapor fluxes and smaller sensible heat fluxes than their terrestrial surroundings. Energy exchange with the atmosphere is dominated by the annual evaporative heat flux. The presence of large lakes in a region substantially decreases the interannual variability in evaporation totals. A hypothetical region with no lakes shows a positive annual terrestrial water balance for wet and average precipitation years and only a small negative water balance for the driest years. The existing lake-rich region has a positive annual water balance only in the wettest years. Comparisons of the region with all small, all medium or all large lake scenarios indicates increased regional evaporation of 8% and 10% respectively for the latter two scenarios. Basin evaporation is a significant source for precipitation within the Mackenzie River Basin during the summer. It is hypothesized that fall and early winter evaporation from medium and large lakes enhances downwind snowfall. In response to climate warming, lake-rich high latitude basins will witness substantially increased annual evaporation.

May land use change reduce the water deficiency problem caused by reduced brown coal mining in the state of Brandenburg?

Lake records provide an important source of information about climate changes on submillenial to millenial timescales during the Holocene. Analyses of lake records from Europe show that there are regionally-coherent patterns of change in lake status (a qualitative index of changes in water depth, area or volume) through the Holocene, reflecting climatically-induced changes in regional water budgets. Rapid changes in lake status occur in many regions of Europe between 9500–9000, 7500–7000 and 4500–4000 yr BP This apparent synchroneity in the timing of changes, although the direction varies from region to region, indicates that the changes in lake status are driven by changes in regional water balance caused by major reorganisations of the atmospheric circulation. Modelling studies indicate that changes in precipitation are the most important cause of changes in lake behaviour across Europe, because the lake water balance in temperate humid regions is largely controlled by runoff from the catchment. Changes in winter precipitation produce a much larger change in runoff and hence in lake response, than changes during the summer growing season. Sensitivity to precipitation changes is enhanced where solar radiation receipts are high: a given change in precipitation will therefore produce a larger response in the lake water balance in southern and eastern Europe than in northern or western Europe. The sensitivity of the lake water balance to changes in precipitation is dependent on the ratio of lake area to catchment area: sensitivity increases as the ratio becomes larger. The lake area to catchment area ratio at which a lake become sensitive varies with the magnitude of the precipitation change. Lake studies have the potential to contribute significantly to documenting and explaining Holocene climate changes across Europe. Continued improvements to the existing lake data base (including improvements to the lake chronologies), coupled with the application of geostatistical and modelling techniques will be required in order to exploit these archives fully.KeywordsLake LevelPrecipitation ChangeLake StatusEuropean LakeReservoir LakeThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Urbanization causes profound changes in the hydrology of developed watersheds with many negative impacts on local, regional, and global energy and water balances, non-point sources of pollution, loss of stream/riparian structure and function, coastal and terrestrial habitats, and changes in atmospheric composition. In an effort to remedy such conditions, many researchers are trying to quantify the range and extent of ecosystem services like thermal regulation, water regulation, aquifer recharge, water quality improvement, habitat, and cultural services that can be achieved by retrofitting engineered Green Infrastructure (GI) into the urban landscape. These niche ecosystems, often funded as a means of managing urban runoff or compensating for habitat loss, typically include soil and vegetation, arranged in new configurations across formerly impervious spaces. The ability of GI to provide meaningful ecosystem services is both enabled, and constrained, by soil moisture, a key driver of ecosystem function and structure. At a particular site, a soil moisture field emerges as the product of soil-water-climate and vegetation interactions. This field then mediates the local water and energy balance, constrains photosynthesis, supports biota, and controls the redox state. Though billions of dollars are currently being spent on GI, very few researchers have been able to document GI's ability to actually provide ecosystem functions and services in different biophysical and climatic regimes. Such work is needed since engineered GI is fundamentally different from other green kinds spaces (e.g. agricultural plots, forests) in that the imported and/or amended soil, bacteria, and newly transplanted vegetation are both in dynamic, early states of development. This dissertation will shed light on the potential role of soil moisture in determining the ecohydrologic performance of engineered GI, a first step in studying GI's ecosystem services. Specifically, we investigate the role that design decisions can have on spatiotemporally variable soil moisture patterns, and the ecosystem services that depend on them. The research includes observations made in the laboratory and in the field, as well as modeling. It is organized into three papers, as follows: · Paper 1 analyzes several years of soil moisture data collected in two urban GI systems. Relationships between precipitation characteristics, season, and hydraulic loading ratio and soil moisture at different depths are quantified. Potential linkages between GI siting and design decisions and ecosystem services are illustrated by also computing evapotranspiration rates at the sites, speculating that site/or climate factors that lead to higher moisture content, engender greater ES associated with ET. · Paper 2 presents laboratory research conducted using a rainfall simulator to demonstrate the ecohydrological significance of GI surface treatments that buffer the impact of raindrops. This paper attempts to: a) determine if vegetation canopies found in typical GI system can protect the soil surface, and reduce crust formation; b) decreasing post-storm surface ponding, and c) increasing the infiltration of water and recharge, when compered to bare soil surfaces. This study focuses on two different scenarios: 1) bare soil and 2) soil protected by synthetic vegetation canopies. Soil moisture, the surface's penetration resistance, and physical measurements of the volume of infiltrate and runoff are made on all two surface treatments after simulated rainfall events. The results are used to develop recommendations regarding surface treatment in engineered urban GI system designs. · Paper 3 attempts to model the observations reported in the companion papers 1 and 2. Specifically, a customized soil moisture model is developed for use in simulating the spatiotemporal variation in the soil moisture regime engineered GI systems. The model is calibrated to in-situ soil moisture observations made at engineered GI sites, and then used to explore the role that decisions regarding the design, construction, operation and maintenance of these unique systems will influence their ability to provide ecosystem services. Specifically, we investigate how differences in hydraulic loading, surface treatment, and precipitation influence the potential for GI systems to yield runoff and recharge under extreme precipitation conditions.

Theories and calculation methods for regional objective ET

Water resources in arid and semi-arid regions are heavily influenced by climate change, water shortage, water regulations, and increased water demands. Monthly discharge is one of the most important factors in hydrological studies. Some of the basins are not equipped with adequate hydrometric equipment. In such a case, average monthly discharge could be estimated by regional monthly water balance models of representative basins. In this study, the following collection of data including: temperature, precipitation and average monthly discharge, and the potential evapotranspiration was calculated by Thornthwaite equations. Remaining parts of water balance equation including: Actual evapotranspiration, soil moisture supply of the area in each month and later months are also estimated via Thornthwaite model. The net water requirements were estimated using the model by assuming that evaporation is the only path for water loss. The results have indicated that timing of recharge is very important in preserving sub-basin hydrology in this region. This modified climate diagram prompts an intuitive understanding of the relationship between recharge and consequent wet spell in Mighan sub-basin of Arak. It may be used as a standard tool to determine adequate water demand in water resources management of the arid regions for wetland protection or restoration.

Analytical framework for the characterization of the space-time variability of soil moisture

In addition to implementing active water resource allocation measures to solve the serious groundwater overexploitation problem caused by large-scale rice planting in the Sanjiang Plain, the reasonable adjustment of rice planting areas is another method of doing so. From the perspective of groundwater recharge and discharge balance, this paper carries out a novel assessment of suitable rice planting areas in the Sanjiang Plain, which is expected to provide a new method for the implementation of land exploitation according to water resource conditions. The technical scheme is as follows: by adjusting the water resource allocation data and rice spatial distribution data in the surface water–groundwater coupled model (baseline model with dynamic land use) in the Sanjiang Plain, static land-use models under different rice planting scales were established. Through simulation and comparison, the rice area that could achieve the balance of groundwater recharge and discharge was considered the suitable rice planting scale in the Sanjiang Plain. The results showed that the average annual change in groundwater storage from 2000 to 2014 simulated by the baseline model was −0.313 billion m3, indicating that there was space for further optimization and adjustment of the rice planting scale in the Sanjiang Plain. By comparing the static land-use models of each year under the current water resource allocation pattern, the rice area of 1.021 million hm2 in 2005 could effectively realize the balance of groundwater recharge and discharge. Under the new water resource allocation pattern of 2035, the water resource conditions in the Sanjiang Plain will be greatly improved, which can support a rice planting scale of 3.058 million hm2 on the basis of ensuring the balance of groundwater recharge and discharge. Our research results can provide a reference for water resource allocation and land-use optimization regulation in the Sanjiang Plain.

Downward shortwave radiation Rsd determines the surface energy balance, alters evapotranspiration and hydrological conditions, and feeds back to the regional and global climate. Large-scale Rsd estimates are usually retrieved from satellite-based top-of-atmosphere radiation and cloud parameters. These estimates are subject to biases and temporal inhomogeneity due to errors in atmospheric parameters, algorithms, and sensor changes. We found that three satellite products overestimate Rsd by 8%–10% over Asia for 1984–2006, particularly in high latitudes. We used the model tree ensemble (MTE) machine-learning algorithm and commonly used ensemble averaging methods to integrate ground observations and satellite products. Validations based on test stations and independent networks showed that the MTE approach reduces the median relative biases from 8%–10% to 2%, which is more effective than the ensemble averaging methods. We further evaluated the impacts of uncertainty in radiation forcing on surface energy and water balances using the land surface model Noah-MP. The uncertainty of radiation data affects the prediction of sensible heat the most, and also largely affects latent heat prediction in humid regions. Holding the other variables constant, a 10% positive bias in Rsd can lead to a 20%–60% positive bias in the monthly median sensible heat. The simulated hydrological responses to changing radiation forcing are nonlinear as a result of the interactions among evapotranspiration, snowpack, and soil moisture. Our analysis concludes that reducing uncertainty of radiation data is beneficial for predicting regional energy and water balances, which requires more high-quality ground observations and improved satellite retrieval algorithms.

Annual evaporation (E) is often determined using the water balance approach, E = P—Q, because precipitation (P) and runoff (Q) are easily obtainable for most parts of the world. From a regional perspective, P and Q are point observations, containing information pertaining both to the regional trend and to the local environment. Trend surface analysis provides a simple method to filter out the local element, permitting a regional estimation of evaporation. This technique was applied to northern Ontario in Canada where a limited P and Q data network covers a vast domain. The resulting estimated evaporation pattern, obtained as a difference between P and Q trend surfaces, is partially compatible with a manually constructed map published by the Government. Discrepancies arise where the data sources are different or inadequate. One major advantage of this method is that, given additional information, the macro-scale estimates of evaporation can be updated easily and objectively.

Climate change is an essential environmental challenge nowadays. Its effects are already being felt in multiple ways. In the future, we will also have to adapt to its effects because of our farming and our daily lives. In our research, we assessed the climate sensitivity of the lowland areas of Hungary through the changes in landscapes and the changes in groundwater resources that have the greatest impact on agriculture, using data from more than half of a century. We have quantified that at the mid-territory level (5-10 thousand km2) the groundwater resources show up to 3-5 km3/year changes in both positive and negative directions due to climatic effects. This significantly exceeds the anthropogenic water uses (the total water use of Hungary is about 5 km3 per year), so the effect of climate is the determining factor in the changes of regional water resources. Future changes in water circulation were modelled using the MIKE-SHE model in two micro-regions in Hungary. We have found that already at the level of the small catchments presented in our study, the water shortage increases by hundreds of millions of m3 per year due to the expected increase in temperature (mainly due to the increase in evapotranspiration), which cannot be compensated by current water supply solutions. Model simulations have confirmed previous results showing that groundwater movements play a very important role even in lowland landscapes. Based on our research, we would like to draw the attention of decision-makers and agricultural experts to the fact that current methods (irrigation, regional water transfers) are not sufficient for successful adaptation to climate change. So, it is not the limited precipitation but the inappropriate agricultural practices that cause a real threat in a changing climate. Based on our research, we have made a proposal for the adaptation of agriculture to climate change.

In the Alps, regional water balances are stressed by an imbalance between the distribution of naturally available water and the anthropogenic water demand. Due to the growing request for freshwater, water resources will have a tendency to decline in future which may cause impacts on water-related ecosystem services for the society. We use European-level statistics to model the alpine drinking water consumption rates of local residents and tourists using the Nomenclature of Units for Territorial Statistics from Eurostat at two levels (NUTS 2 and NUTS 3). Using the spatial distribution of local residents and tourists as well as the compiled daily water consumption rates, we modelled the amount of water consumed between 1990 and 2008. In the Greater Alpine Region (GAR) water consumption rates from the population on NUTS 3 level increased from 8.3 million m3 per day during the 1990s to 11.2 million m3 per day in 2008. The water consumption rates of both residents and tourists show an increase in central southern areas of the GAR from 1990 to 2000. This trend continues to the south-western part of the GAR between 2000 and 2008. Thus, the drinking water consumption of inhabitants and tourists is highest in places where hydro-climate changes indicate trends of declining naturally available water resources.

Central Asia and Xinjiang, China are conjunct areas, located in the hinterland of the Eurasian continent, where the snowfall is an important water resource supplement form. The induced seasonal snow cover is vita factors to the regional energy and water balance, remote sensing plays a key role in the snow mapping filed, while the daily remote sensing products are normally contaminated by the occurrence of cloud, that obviously obstacles the utility of snow cover parameters. In this paper, based on the daily snow product from Moderate Resolution Imaging Spectroradiometer (MODIS A1), a cloud removing method was developed by considering the regional snow distribution characteristics with latitude and altitude dependence respectively. In the end, the daily cloud free products was compared with the same period of eight days MODIS standard product, revealing that the cloud free snow products are reasonable, while could provide higher temporal resolution, and more details over Center Asia and Xinjiang Province.

The presence of snow cover affects the regional energy and water balance, thus having a significant impact on the global climate system. Temporal knowledge of the onset of snow melt and snow water equivalent (SWE) values are important variables in the prediction of flooding, as well as water resource applications such as reservoir management and agricultural activities. Microwave remote sensing techniques have been effective for monitoring snow pack parameters (snow extent, depth, water equivalent, wet/dry state). Coincident ground data, airborne polarimetric C-band (5.3 GHz) Synthetic Aperture Radar (SAR) and passive microwave radiometer data (19, 37 and 85 GHz) were collected on four dates (1 December 1997, 6 March 1998, 12 March 1998 and 9 March 1999) over two flight lines in Eastern Ontario, Canada. The multitemporal, multi-sensor data were analysed for changes in SAR polarimetric signatures and microwave brightness temperatures as a function of changing snow pack parameters. Results indicate that certain parameters such as linear polarizations and pedestal height are sensitive to changes in snow pack parameters, and respond differently to various snow conditions. SWE values derived from the passive microwave brightness temperatures compare well with ground measurements, with the exception of low snow volume and in the presence of significant ice layers.

Abstract. The presence of snow cover has significant impacts on the both global and regional climate and water balance on earth. The accurate estimation of snow cover area can be used for forecasting runoff due to snow melt and output of hydroelectric power. With development of remote sensing techniques at different scopes in earth science, enormous algorithms for retrieval hydrometeor parameters have been developed. Some of these algorithms are used to provide snow cover map such as NLR with AVHRR/MODIS sensor for Norway, Finnish with AVHRR sensor for Finland and NASA with MODIS sensor for global maps. Monitoring snow cover at different parts of spectral electromagnetic is detectable (visible, near and thermal infrared, passive and active microwave). Recently, specific capabilities of active microwave remote sensing such as snow extent map, snow depth, snow water equivalent (SWE), snow state (wet/dry) and discrimination between rain and snow region were given a strong impetus for using this technology in snow monitoring, hydrology, climatology, avalanche research and etc. This paper evaluates the potentials and feasibility of polarimetric ground microwave measurements of snow in active remote sensing field. We will consider the behavior co- and cross-polarized backscattering coefficients of snowpack response with polarimetric scatterometer in Ku and L band at the different incident angles. Then we will show how to retrieve snow cover depth, snow permittivity and density parameters at the local scale with ground-based SAR (GB-SAR). Finally, for the sake of remarkable significant the transition region between rain and snow; the variables role of horizontal reflectivity (ZHH) and differential reflectivity (ZDR) in delineation boundary between snow and rain and some others important variables at polarimetric weather radar are presented.