Evolution Of Water Cycle Research Articles

Water cycle evolution in the Haihe River Basin and its relationship with landscape pattern changes

Landscape patterns and water cycle processes have changed significantly in recent decades as a result of intensive interference from human activities. Although the intensification of the global water cycle is well illustrated from a climate change perspective, using landscape index to characterize the evolution of water cycle have been less explored. This study aimed to investigate the water cycle status and its evolution from the perspective of landscape patterns. A water cycle intensity (WCI) evaluation model based on the landscape index was developed. Defined as the ratio of the water resource circulation to the natural circulation, the WCI was used to analyze the water cycle evolution trend in each region of the Haihe River Basin. Through correlation and dynamic change trend analyses, the patch density (PD) of the urban areas and runoff landscape index (RLI) were identified as synchronizing with the WCI changes. The mathematical relationships between the landscape indicators (PD and RLI) and WCI were explored. Thereafter, according to the WCI development and its impact on the ecological environment, three categories of water cycle statuses (WCSs) were proposed: the natural circulation status (NCS), moderately developed status (MDS), and overdeveloped status (ODS). The WCS evolution trend in the Haihe River Basin was evaluated and the results showed all regions have evolved into a state of ODS with WCIs above 35% in 2010 and five of the plain regions greater than 80%. The proposed approach can be effectively applied to evaluating and predicting WCS in ungauged basins or future landcover scenarios, thereby providing a new perspective and effective tools for water resource management.

Assessment of the spatiotemporal evolution and driving forces of meteorological drought in the North China Plain

AbstractWith the changing trend of global temperature increase, the occurrence of drought events can no longer be ignored. An investigation of the spatiotemporal evolution characteristics of meteorological droughts and their responses to climatic variables can elucidate the mechanisms of the water cycle evolution in changing environments. In the present study, the standardized precipitation evapotranspiration index was used to characterize meteorological drought in the North China Plain (NCP) from 1970 to 2020. The spatiotemporal patterns of meteorological drought were analysed, and the contributions of climatic factors on annual and seasonal time scale drought evolution were determined. The results revealed that meteorological drought showed a decreasing trend (−0.07/10a) in the NCP from 1970 to 2020 and the most severe meteorological drought occurred in winter, with 56.56% of the region experiencing an increased drought trend in this season. Significant trends were identified for mean temperature (Tmean), temperature difference, and wind speed in the drought trend evolution. Precipitation (P) and Tmean were the primary controlling factors of the drought evolution. The strongest effect on drought change were exerted by P in spring (contribution [Con]: 1.57%), summer (Con: 1.79%) and autumn (Con: 2.43%), and the negative contribution of Tmean in winter (Con: −3.64%) was greater than the positive contribution of P (Con: 2.69%). The contribution of climatic variables to drought were increased by regional altitude difference. The results reveal a novel explanatory mechanism of climate change's effects on drought.

The importance of studying the geological evolution of water cycle

The importance of studying the geological evolution of water cycle

Evolution of water cycle in deep time: Current research status and key questions

Evolution of water cycle in deep time: Current research status and key questions

Quantifying the impact of climate change and human activities on runoff at a tropical watershed in South China

Different regions exhibit different response patterns of hydrological process changes under changing environments. The hydrological response mechanism of underlying surface changes in tropical rainforest regions remains uncertain, so there is an urgent need to study the causes of hydrological changes in typical tropical watersheds. The sequential clustering analysis and Pettitt-Mann-Whitney test were employed to detect abrupt change points of runoff series for the Wanquan River Basin in the tropics, and the series was then divided into pre-impact period (1967–1990) and post-impact period (1991–2014). And the Soil and Water Assessment Tool (SWAT) model was used to simulate the runoff to quantify the impact of climate change, land use change and other human activities on runoff, which the latter two collectively referred to as “human activities” in this study. The findings reveal: 1) runoff series showed an abrupt change and a downward trend around the year 1990; the SWAT model has a good simulation in the Wanquan River Basin during the pre-impact period; the coefficients of determination (R2) for the calibration and validation periods are both 0.91, and the Nash-Sutcliffe model efficiency coefficients (NSE) for the calibration and validation periods are 0.89 and 0.86, respectively. 2) There was a considerable change in land use between 1967 and 2014, as evidenced by a decrease of 29.54% in natural forest and an increase of 54.90% in rubber. These land use changes were mostly caused by the transformation of tropical rainforests into rubber forests and orchards. 3) Runoff declined in the post-impact period from the pre-impact period, with climate change, land use change, and other human activities contributing 44.05%, 10.83%, and 45.12% to the runoff change, respectively. The conversion of tropical rain forests to rubber forests and orchards has indirectly led to a reduction in runoff. These results can provide a reference for understanding the evolution of water cycle for other tropical rivers.

Construction of root tip density function and root water uptake characteristics in alpine meadows.

Accurate calculation of root water uptake (RWU) is the key to improving vegetation water use efficiency and identifying water cycle evolution patterns, and root tips play an important role in RWU. However, most of the current RWU models in the alpine meadow are calculated based on the root length density (RLD) function. In this study, a large number of roots, soil hydraulic conductivity, and physicochemical property indices were obtained by continuous field prototype observation experiments for up to 2 years. It was found that the RLD and root tip density (RTD) in alpine meadows decrease by 16.2% and 14.6%, respectively, in the wilting stage compared to the regreening stage. The RTD distribution function of the alpine meadow was constructed, and the RWU model was established accordingly. The results show that the RTD function is more accurate than the RLD function to reflect the RWU pattern. Compared with RLD, the simulated RWU model constructed by using RTD as the root index that can effectively absorb water increased by 24.64% on average, and the simulated values were more consistent with the actual situation. It can be seen that there is an underestimation of RWU calculated based on the RLD function, which leads to an underestimation of the effect of climate warming on evapotranspiration. The simulation results of the RWU model based on RTD showed that the RWU rate in the regreening stage increased by 30.24% on average compared with that in the wilting stage. Meanwhile, the top 67% of the rhizosphere was responsible for 86.76% of the total RWU on average. This study contributes to the understanding of the alpine meadow water cycle system and provides theoretical support for the implementation of alpine meadow vegetation protection and restoration projects.

Spatial difference analysis of the runoff evolution attribution in the Yellow River Basin

Attribution analysis of runoff evolution under changing environmental conditions is currently a hot yet challenging topic in hydrology research. In this study, the Budyko method was used to quantitatively identify the effects of climate conditions and the underlying surface such as topography, land use and vegetation cover on the runoff changes in the Yellow River Basin during 1961–2018, and to clarify the spatial differences in the sensitivity and attribution of the runoff evolution by dividing the entire basin into sub-basins. The results show that the runoff was more sensitive to the underlying surface and precipitation changes than to the potential evaporation. The sensitivity coefficients decreased from upstream to downstream and the aridity index increased. The contribution rates of the climatic and the underlying surface changes to the runoff changes were 10.3–36.8% and 62.9–88.7%, respectively, and the underlying surface changes were the dominant factor causing the decrease in the runoff. Climate change led to increased runoff in the upper reaches and decreased runoff in the middle and lower reaches; while the underlying surface changes led to decreased runoff throughout the entire basin, especially in the middle reaches of the Yellow River. The quantified spatial differences in the runoff evolution attribution can help improve regional water resource management and provide theoretical support for studying the water cycle evolution mechanism in the Yellow River Basin.

Discussion on Core Technique and General Software Platform of River Water Resources Regulation in China

Due to the aggravation of human activities and global climate changes in recent decades, catchment water cycle has experienced strong variation. The world is faced with profound water crisis, and water problems are especially severe and water disasters are of high frequency in China. Water problems have become significant obstacle factors for realizing sustainable development, which greatly threatens national economy and ecological safety. Given the scientific background of catchment water cycle evolution and water resources comprehensive regulation, we propose the method of solving water problems through water resources operation based on dualistic water cycle theory and discuss the developing status and existing problems of current water resources operation in China. On this basis, we also put forward the technical framework and key process of water resources regulation, which integrates the six links of monitoring, simulation, evaluation, forecasting, regulation and control. Furthermore, aiming at the background of the second phase of National Water Monitoring Capacity Building Project, we introduce a nationwide general software platform for water resources regulation. This platform will realize business collaboration and information sharing among three-scale platform of Ministry of Water Resources, basin authorities and provincial level, so as to overall improve the ability of water resources regulation and decision-making.

Environmental controls on stable isotopes of precipitation in Lanzhou, China: An enhanced network at city scale

Stable hydrogen and oxygen isotopes in precipitation are very sensitive to environmental changes, and can record evolution of water cycle. The Lanzhou city in northwestern China is jointly influenced by the monsoon and westerlies, which is considered as a vital platform to investigate the moisture regime for this region. Since 2011, an observation network of stable isotopes in precipitation was established across the city, and four stations were included in the network. In 2013, six more sampling stations were added, and the enhanced network might provide more meaningful information on spatial incoherence and synoptic process. This study focused on the variations of stable isotopes (δ18O and δD) in precipitation and the environmental controls based on the 1432 samples in this enhanced network from April 2011 to October 2014. The results showed that the precipitation isotopes had great spatial diversity, and the neighboring stations may present large difference in δD and δ18O. Based on the observation at ten sampling sites, an isoscape in precipitation was calculated, and the method is useful to produce isoscape for small domains. The temperature effect and amount effect was reconsidered based on the dataset. Taking meteorological parameters (temperature, precipitation amount, relative humidity, water vapor pressure and dew point temperature) as variables in a multi-linear regression, the result of coefficients for these meteorological parameters were calculated. Some cases were also involved in this study, and the isotopic characteristics during one event or continuous days were used to understand the environmental controls on precipitation isotopes.

Research framework of integrated simulation on bilateral interaction between water cycle and socio-economic development

The mechanism of bilateral interaction between natural water cycle evolution and socio-economic development has been obscured in current research due to the complexity of the hydrological process and the socio-economic system. The coupling of economic model CGE (Computable General Equilibrium) and distributed hydrological model WEP (Water and Energy transfer Processes) provides a model-based tool for research on response and feedback of water cycle and social development, as well as economic prospects under the constraint of water resources. On one hand, water policies, such as water use limitation and water price adjustment under different levels of socio-economic development, are to be evaluated by CGE model as assumed conditions and corresponding results of water demand could be put into WEP model to simulate corresponding response during the whole process of water cycle. On the other hand, variation of available water resources quantity under different scenarios simulated by WEP model may provide proper limitation for water demand in CGE model, and corresponding change of economic factors could indicate the influence of water resources constraints on socio-economic development. The research is believed to be helpful for better understanding of bilateral interaction between water and society.

Does GRACE see the terrestrial water cycle “intensifying”?

AbstractSeveral researchers have postulated that, under a changing climate due to anthropogenic forcing, an intensification of the water cycle is already under way. This is usually related to increases in hydrological fluxes as precipitation (P), evapotranspiration (E), and river discharge (R). It is under debate, however, whether such observed or reconstructed flux changes are real and on what scales. Large‐scale increase or decrease of the flux deficit (P‐E‐R), i.e., flux changes that do not compensate, would lead to acceleration or deceleration of water storage anomalies potentially visible in Gravity Recovery and Climate Experiment (GRACE) data. In agreement with earlier studies, we do find such accelerations in global maps of gridded GRACE water storage anomalies over 2003–2012. However, these have been generally associated with interannual and decadal climate variability. Yet we show that even after carefully isolating and removing the contribution of El Niño that partially masks long‐term changes, using a new method, accelerations of up to 12 mm/yr2 remain in regions such as Australia, Turkey, and Northern India. We repeat our analysis with flux fields from two global atmospheric reanalyses that include land surface models (ERA‐Interim and MERRA‐Land). While agreeing well with GRACE on shorter time scales, they fall short in displaying long‐term trends corresponding to GRACE accelerations. We hypothesize that this may be due to time‐varying biases in the reanalysis fluxes as noticed in other studies. We conclude that even though its data record is short, GRACE provides new information that should be used to constrain future reanalyses toward a better representation of long‐term water cycle evolution.

The Impacts of the Basin Scale Hydrological Cycle to Water Budget of Wetlands in Nenjiang River Basin

The relationship between the water budget of wetlands and the water cycle process in local river basin is bidirectional. The recovery and function performance of the wetland are based on this relationship. Hydrological models are the effective tool to detecting this link. The distributed hydrologic model was the key supports in this study and was used to quantitative identify the change of water budget of the wetlands which was impacted by the water cycle evolution in Nenjiang River basin in Northeast China. The results indicated that precipitation, runoff and evapotranspiration both in the basin and wetlands present similar declining trend. The precipitation is the major recharge source, and the evapotranspiration is the primary output of wetlands. The value of mean change in storage of the wetlands is negative which is caused by the decrease of the area of wetlands. The results of land use pattern evolution change surface inflow in the wetlands in the basin scenarios simulation indicated. These results suggested that water budget of wetlands is influenced by water cycle in basin. And some reasonable measures for wetlands management should not only base on its features, but also pay attention to hydrological regime in basin.

Theoretical framework of dualistic nature–social water cycle

The global climate change and intensification of human activities in recent decades have made profound changes in hydrological cycle processes and water resources, and produced serious water problems and water crisis in many areas. The main reason is that the driving force of water cycle, the structure of water cycle, and the parameters of water cycle have dualistically evolved under the influence of human activities, and consequently resulted in reduction of runoff water resources, water pollution, and degradation of natural ecosystems. In order to realize of the safety aim of water supply, water environment, and ecosystem in area which is short of water resources, scientific regulation of water resources must take basin water cycle system as the unified base, and the first scientific basis is the awareness of the internal mechanism and law of water cycle evolution under highly intensive human activities. This article discussed four aspects of dualistic water cycle evolution, including its history in China, its theory, its characteristics in a typical basin, and its description of integral structure, along with the conceptive model system to quantify it. This article can be a reference to the basic cognition of water cycle evolution in a changing environment, and the study of water resources reduction reasons in the contemporary age.

Evolutionary mechanism of water cycle and efficient utilization of water resources in the Haihe River Basin

Water cycle in the river basin constitutes the objective basis of water resources evolution. Whatever their manifestations, water resources problems can all attribute to the imbalances caused by the evolution of water cycle or its associated processes in the river basin. Various types of water activities for solution to water problems are in nature a regulation of natural-social dualistic water cycle or its associated processes in the river basin. China is one of those countries which are faced with the most violent water cycle evolution and serious water problems with the Haihe River Basin as the

Water cycle evolution in the Haihe River Basin in the past 10000 years

The water shortage problem in the Haihe River Basin is the most severe in China, and has restricted its economic development. Over-extraction of groundwater has been very severe in the past 30 years. To solve this problem, scientific decisions should be made from a historical perspective. It is important to describe water cycle evolution in the Haihe River basin over the past 10000 years. Datasets of paleoclimate, paleogeography, palynoflora, historical record, isotopic abundance ratio and content were collected for research on different time scales. Some interesting conclusions were drawn by a comprehensive analysis method. First, radiation was the intrinsic force driving the evolution of water cycle. Generally, precipitation increased with temperature. Second, precipitation was high during 8 ka-5 ka B.P., the so-called Yangshao warm period of the Middle Holocene, which recharged the major part of the Quaternary groundwater. Third, heavy floods during this period transported sediment to the seaside, forming the Coastal Plain where cities such as Tianjin, Huanghua, Cangzhou are now located. In the last 3000 years, intermittent moderate floods did not have enough energy to transport sediment to the sea. Rivers usually overflowed in the piedmont region of the Taihang Mountains, and sediment deposited there formed the Piedmont Plain, where locate Shijiazhuang, Xingtai, Handan, Baoding and other cities. Precipitation had a high correlation with temperature in Haihe River Basin in the past 10000 years: the high temperature usually coupled with high precipitation. Today precipitation in the Haihe River Basin is relatively low, owing to low temperature. This study reveals the relationship between temperature, precipitation and river networks in the past 10000 years in Haihe River Basin, which has great scientific and practical importance in understanding the current water circulation and water shortage.