Hydroecological Systems Research Articles

Modelling impacts of climate change on coastal West African rainfall

Several tropical regions of the world, including West Africa are strong climatic hotspots where increase in extreme climatic events (e.g., droughts) impact water resources and hydro-ecological systems. Even though the West African Sahel has been widely studied, reports on the rainfall climatology of coastal West Africa are considerably limited. Assessing the evolutionary changes in rainfall in this region is crucial to improving the understanding on the impacts of global climate systems on rainfall variability. The main aim of this study is to assess the impact of climate change on the characteristics (mean annual, wettest month, driest month, and mean monthly) of coastal West African rainfall using General Circulation Model and two representative concentration pathways (RCP 4.5 and RCP 8.5 emission scenarios). Climate teleconnection induced rainfall is quantified using the partial least squares regression, and the dominant patterns of rainfall variability in the region are also assessed. The results indicate that areas along the coast with leading modes of rainfall variability and characterized by bimodal rainfall patterns are projected to receive highest rainfall in the mid (2041–2070) and end (2071–2100) of the century. However, inland areas are expected to receive low rainfall under the influence of both emission scenarios. An exception to this is the inland middle belt in Nigeria, which is projected to receive more rainfall than its surrounding areas. These results imply an intensification of the water cycle along the coastal region that could lead to increasing propensity of flood and drought events. Finally, Togo, Côte d’Ivoire, southern Ghana, Benin are hotspots in coastal West Africa where climate teleconnection patterns induce changes in rainfall.

Spatial and Temporal Shifts in Historic and Future Temperature and Precipitation Patterns Related to Snow Accumulation and Melt Regimes in Alberta, Canada

Shifts in winter temperature and precipitation patterns can profoundly affect snow accumulation and melt regimes. These shifts have varying impacts on local to large-scale hydro-ecological systems and freshwater distribution, especially in cold regions with high hydroclimatic heterogeneity. We evaluate winter climate changes in the six ecozones (Mountains, Foothills, Prairie, Parkland, Boreal, and Taiga) in Alberta, Canada, and identify regions of elevated susceptibility to change. Evaluation of historic trends and future changes in winter climate use high-resolution (~10 km) gridded data for 1950–2017 and projections for the 2050s (2041–2070) and 2080s (2071–2100) under medium (RCP 4.5) and high (RCP 8.5) emissions scenarios. Results indicate continued declines in winter duration and earlier onset of spring above-freezing temperatures from historic through future periods, with greater changes in Prairie and Mountain ecozones, and extremely short or nonexistent winter durations in future climatologies. Decreases in November–April precipitation and a shift from snow to rain dominate the historic period. Future scenarios suggest winter precipitation increases are expected to predominantly fall as rain. Additionally, shifts in precipitation distributions are likely to lead to historically-rare, high-precipitation extreme events becoming more common. This study increases our understanding of historic trends and projected future change effects on winter snowpack-related climate and can be used inform adaptive water resource management strategies.

Drought prediction in the Lepelle River basin, South Africa under general circulation model simulations

This study aims to evaluate changes in the frequency and severity of historical droughts (1980–2018) and then model future droughts occurrences (2019–2099) in the Lepelle River Basin (LRB), using Intergovernmental Panel on Climate Change (IPPC) General Circulation Model (GCM) simulations for two representative concentration pathways (RCP8.5 and RCP4.5). Firstly, the present-day and future hydrology of the LRB are modelled using the weather evaluation and planning (WEAP) model. Mann–Kendall tests are conducted to identify climate trends in the LRB. The reconnaissance drought in-dex (RDI) and the streamflow drought index (SDI) are employed to explore hydro-meteorological droughts in the Lepelle River Basin, South Africa. The RDI and SDI are plotted over time to assess drought magnitude and duration. The simulated temporal evolution of RDI and SDI show a significant decrease in wetting periods and a concomitant increasing trend in the dry periods for both the lower and middle sections of the LRB under RCP4.5 as the 22nd century is approached. Lastly, the Spearman and Pearson correlation matrix is used to determine the degrees of association between the RDI and SDI drought indices. A strong positive correlation of 0.836 is computed for the middle and lower sections of the LRB under the RCP8.5 forcing. Further findings indicate that severe to extreme drought above –2.0 magnitude are expected to hit the all three sec-tions of the LRB between 2080 and 2090 under RCP8.5. In the short term, it is suggested that policy actions for drought be implemented to mitigate possible impacts on human and hydro-ecological systems in the LRB.

Large intact forest landscapes and inclusive conservation: a political ecological perspective

Intact Forest Landscapes (IFLs) are global conservation units that aim to combat fragmentation, alteration, degradation, and loss of global forests. ILFs are typically recognized for their biodiversity, carbon storage, protection of hydroecological systems and other ecosystem services. However, IFLs are distinctive among other conservation efforts because they do not immediately prioritize conservation approaches that have goals of alleviating human poverty or improving well-being. The prevailing view is that IFL conservation should engage with ecocentric models of conservation. In this article, we leverage political ecology's analytical attention to power, institutions, identities, and scales to make suggestions on ways in which to integrate biocentric conservation considerations into IFL practices. From a scoping literature review, we found the following areas are especially critical for the future of IFL conservation: (1) prioritizing Indigenous Peoples and Local Communities (IPLC) as actors and beneficiaries of conservation; (2) identifying the value of knowledge integration and co-production for conservation; (3) addressing heterogenous communities and equity impacts, and (4) the need for procedural mechanisms in conservation initiatives that support nesting Indigenous Peoples and Local Communities management and governance in polycentric systems. Furthermore, the development of diagnostic questions of scaling community-based conservation and adaptive strategies beyond their original scope in terms of community definitions, landscape and political context may be beneficial for addressing multi-stakeholder needs, identifying more equitable approaches, sharing strategies and obtaining successful outcomes in IFL conservation.Keywords: Indigenous peoples and local communities, large intact landscapes, forests, conservation

Evolutional characteristics of hydro-meteorological drought studied using standardized indices and wavelet analysis

The study presents a more recent historical analysis of hydro-meteorological droughts in the Olifants Basin, South Africa from 1980 to 2013 using the Standardized Precipitation Index (SPI), the Standardized Precipitation Evapotranspiration Index (SPEI) and the Streamflow Drought Index (SDI). Time series of SPI, SPEI and SDI were analyzed for drought intensity and duration using wavelet analysis. Results indicate different periodicity and temporal variability of drought with significant meteorological drought incidence in 1991–2004 within the 2–8-year band and hydrological drought in 1996–2004 within the 3–5-year band. Spearman correlation analysis revealed a significant correlation (p < 0.01) between SPI and SPEI irrespective of the timescale. However, the strongest correlation occurred at the same timescale for SPI and SPEI: 3-month timescale (r = 0.904, p < 0.01), 6-month timescale (r = 0.936, p < 0.01), 9-month timescale (r = 0.946, p < 0.01) and 12-month timescale (r = 0.947, p < 0.01). A significant relation also existed between SDI and SPI (r = 0.731, p < 0.01) as well as between SDI and SPEI (r = 0.631, p < 0.01). Findings further indicate varying degrees of drought ranging from near normal to extremely dry conditions during 1980–2013. It is expected that strategies and policy actions on drought factor in the recurring nature of droughts so as to minimize the negative impact on water resources and other human–hydro-ecological systems.

Modelling and forecasting the hydroecological systems pollution dynamics by using a chaos theory methods: II. advanced chaos data on pollution of the Small Carpathians river’s watersheds

This paper goes on our advanced quantitative studying results of a pollution dynamics for variations hydroecological systems, namely, the nitrates etc concentrations dynamics for a number of the Small Carpathians river’s watersheds in the Eastern Slovakia. The different methods and algorithms of the chaos theory (chaos-geometric approach) and dynamical systems theory have been used in the advanced versions. New more exact data on chaotic behaviour of the nitrates concentration time series in the watersheds of the Small Carpathians are presented. In previous paper [1] to reconstruct the corresponding attractor, the time delay and embedding dimension have been needed and computed. The parameters are determined by the methods of autocorrelation function and average mutual information. Besides, there are used the advanced versions of the correlation dimension method and algorithm of false nearest neighbours. The Fourier spectrum of the con-centration of nitrates in the water catchment area Ondava: Stropkov for the period 1969-1996 is listed. Here we present new advanced data on the correlation dimension (d2), embedding dimension (dE), Kaplan-Yorke dimension (dL), average limit of predictability (Prmax) and parameter K for the nitrates concentrations in the watersheds of the Small Carpathians.

Wavelet and multifractal analysis of the nonlinear structures in chaotic processes for hydroecological systems

This paper goes on our investigations of the fractal structures in the chaotic and turbulent processes and connected with a great importance the experimental and theoretical studying of the non-linear dynamical systems with aim to discover the fractal features and elements of dynamical chaos. In this paper on the basis of wavelet analysis and multifractal formalism it is carried out an analysis of fractal structures in the chaotic processes (the time series of the nitrates concentrations in the Small Carpathians river’s watersheds Svidnik-Ondrava in the Earthen Slovakia) and the spectrum of the fractal dimensions has been computed. It is carried out numerical modelling and fulfilled a comparison of theoretical data with the earlier received estimates on the basis of other fractal formalism algorithm.

Analysis and forecast of the environmental radioactivity dynamics based on methods of chaos theory: general scheme and some application

We present firstly a new whole technique of analysis, processing and forecasting environmental radioactivity dynamics, which has been earlier developed for the atmospheric pollution dynamics analysis and investigation of chaotic feature sin dynamics of the typical hydroecological systems. The general formalism include: a) A general qualitative analysis of dynamical problem of the environmental radioactivity dynamics (including a qualitative analysis from the viewpoint of ordinary differential equations, the “Arnold-analysis”); b) checking for the presence of a chaotic (stochastic) features and regimes (the Gottwald-Melbourne’s test; the method of correlation dimension); c) Reducing the phase space (choice of the time delay, the definition of the embedding space by methods of correlation dimension algorithm and false nearest neighbor points); d) Determination of the dynamic invariants of a chaotic system (Computation of the global Lyapunov dimension λa; determination of the Kaplan-York dimension dL and average limits of predictability Prmax on the basis of the advanced algorithms; e) A non-linear prediction (forecasting) of an dynamical evolution of the system. The last block indeed includes new (in a theory of environmental radioactivity dynamics) methods and algorithms of nonlinear prediction such as methods of predicted trajectories, stochastic propagators and neural networks modelling, renorm-analysis with blocks of the polynomial approximations, wavelet-expansions etc.

Social, hydro-ecological and climatic change in the southwest coastal region of Bangladesh

This study investigates the historical development of the southwest coastal region of Bangladesh through the lens of human-delta co-evolutionary system. The change process of social and hydro-ecological systems is described based on the drivers–pressure–state–impact–response (DPSIR) framework. The multiple physical and socio-economic drivers such as climatic change, upstream development, geologic process, land use change-affected river flow, salinity, water logging and cyclones are creating adverse impacts on ecology (e.g. mangrove forest) and society (e.g. population migration). Existing management practices such as the Coastal Embankment project (CEP) also created adverse impacts on social–ecological system. In addition to the geology of this region that plays the major role in the delta development process, human interventions such as large coastal development projects have intervened the land formation processes. The trends and impacts of these changes along the coast unfold the necessity of integrated management approach such as Integrated Water Resources Management (IWRM) and Integrated Coastal Zone Management (ICZM). Comprehensive understanding of social and hydro-ecological system in southwest coastal region through DPSIR approach presented in this study can provide effective solution for implementing ongoing management strategies.

Evaluating Flow Metric-Based Stream Classification Systems to Support the Determination of Ecological Flows in North Carolina

Hydroecological classification systems are typically based on an assemblage of streamflow metrics and seek to divide streams into ecologically relevant classes. Assignment of streams to classes is suggested as an initial step in the process of establishing ecological flow standards. We used two distinct hydroecological river classification systems available within North Carolina to evaluate the ability of a hydrologic model to assign the same classes as those determined by observed streamflows and to assess the transferability of such systems to ungaged streams. Class assignments were examined by rate of overall matches, rate of class matches, spatial variability in matches, and time period used in class assignment. The findings of this study indicate assignments of stream class: (1) are inconsistent among different classification systems; (2) differ between observed and modeled data; and (3) are sensitive to the period of record within observed data. One clear source of inconsistency/sensitivity in class assignments lies with the use of threshold values for metrics that distinguish stream classes, such that even small changes in metric values can result in different class assignments. Because these two hydroecological classification systems are representative of other classification systems that rely on quantitative decision thresholds, it can be surmised that the use of such systems based on stream flow metrics is not a reliable approach for guiding ecological flow determinations.

Геометрия Хаоса: Усовершенствованный численный подход к изучению хаотической динамики некоторых гидроэкологических систем

This paper goes on our work on application of the chaos theory and non-linear analysis technique to studying chaotic features of different nature systems. Here we present new results of using an advanced chaos-geometric approach to treating chaotic pollution dynamics in the hydroecological systems, in particular, forested watersheds. Generally, an approach combines together application of the advanced mutual information scheme, Grasberger-Procachi algorythm, Lyapunov exponent's analysis etc

Геометрия Хаосу: Усовершенствованный численный подход к изучению хаотической динамики некоторых гидроэкологических систем

In the paper we go on our work on application of the chaos theory and non-linear analysis technique to studying chaotic features of different nature systems. Here there are presented the results of using an advanced chaos-geometric approach to treating chaotic dynamics in definiete hydroecological systems. Generally, an approach combines together application of the advanced mutual information scheme, Grrasberger-Procachi algorythm, Lyapunov exponent's analysis etc

Effective Treatment of Nutrients by Adsorption onto the Surface of a Modified Clay and a Toxicity Evaluation of the Adsorbent

A pure clay ball and surface-modified clay ball were investigated to remove phosphate from synthetic wastewater; phosphate causes eutrophication in hydro-ecological systems. Adsorption tests of phosphate from aqueous solutions onto two types of adsorbents were conducted. The maximum phosphate adsorption capacities of the pure and surface-modified clay ball were found to be 0.084 and 8.869 mg/g, respectively. In a fixed-bed column packed with surface-modified clay balls, the first breakthrough of phosphate appeared after approximately 4000 min. In addition, the phosphate adsorbed on the surface-modified clay ball was effectively desorbed using a 1 M zirconium sulfate solution, and the adsorbent was regenerated for four adsorption and three desorption cycles by maintaining the adsorption capacity at the value before regeneration. X-ray diffraction (XRD), scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy (EDX), and Brunauer-Emmett-Teller (BET) analysis method were performed to reveal the characteristics of the surface-modified clay ball. Cytotoxicity experiment was conducted on the developed adsorbents, and as a result, these showed low cytotoxic effect on the human cells. These results indicated that the surface-modified clay ball, due to the low cost, high adsorption capacity, and non-toxicity, has the potential to be utilized in the cost-effective removal of phosphate from aqueous solutions.

Water cycle modelling of peri-urban hydroecological systems: a case study of the South Creek catchment, Australia

Modelling offers a time efficient and cost-effective approach to integrate and analyse different components of complex peri-urban hydroecological systems. This paper evaluates and applies a catchment water balance model (Peri-Urban SimHyd) developed to simulate the complete water cycle of the South Creek catchment, a complex peri-urban catchment in Western Sydney (Australia). Peri-Urban SimHyd combined the modelling of daily rainfall-runoff from both impervious and pervious surfaces with the modelling of monthly reticulated potable water supply, wastewater flows, and surface and groundwater extractions, to simulate the monthly water balance of the catchment. The model was successful (the Nash-Sutcliffe efficiency >0.68) in simulating the monthly total wastewater discharges and streamflows in the South Creek and its main tributary, the Eastern Creek, over a period of 15 years (1992–2006). The model performance was found to be suitable for simulating macro water balance and catchment yield but not for low streamflow hydrographs. Further, the model demonstrated its applicability in assessing the impacts of water cycle management strategies, i.e. ‘replacement flows’ and ‘water smart farms’ scenarios, on monthly and annual streamflows in the South Creek catchment. In general, Peri-Urban SimHyd has a generic structure and can be employed to assess impacts of various ‘what if’ scenarios on water cycle and streamflows in other peri-urban hydroecological systems.

A comprehensive sustainability appraisal of water governance in Phoenix, AZ

In Phoenix, Arizona and other metropolitan areas, water governance challenges include variable climate conditions, growing demands, and continued groundwater overdraft. Based on an actor-oriented examination of who does what with water and why, along with how people interact with hydro-ecological systems and man-made infrastructure, we present a sustainability appraisal of water governance for the Phoenix region. Broadly applicable to other areas, our systems approach to sustainable water governance overcomes prevailing limitations to research and management by: employing a comprehensive and integrative perspective on water systems; highlighting the activities, intentions, and rules that govern various actors, along with the values and goals driving decisions; and, establishing a holistic set of principles for social–ecological system integrity and interconnectivity, resource efficiency and maintenance, livelihood sufficiency and opportunity, civility and democratic governance, intra- and inter-generational equity, and finally, precaution and adaptive capacity. This study also contributes to reforming and innovating governance regimes by illuminating how these principles are being met, or not, in the study area. What is most needed in metropolitan Phoenix is enhanced attention to ecosystem functions and resource maintenance as well as social equity and public engagement in water governance. Overall, key recommendations entail: addressing interconnections across hydrologic units and sub-systems (e.g., land and water), increasing decentralized initiatives for multiple purposes (e.g., ecological and societal benefits of green infrastructure), incorporating justice goals into decisions (e.g., fair allocations and involvement), and building capacity through collaborations and social learning with diverse interests (e.g., scientists, policymakers, and the broader public).