Catchment Units Research Articles

Deep learning prediction of rainfall-driven debris flows considering the similar critical thresholds within comparable background conditions

Machine learning has been widely applied to predict the spatial or temporal likelihood of debris flows by leveraging its powerful capability to fit nonlinear features and uncover underlying patterns or rules in the complex formation mechanisms of debris flows. However, traditional approaches, including some current machine learning-based prediction models, still have limitations when used for debris flow prediction. These include the lack of a specific network structure or model to consider the updating of debris flow critical conditions in relation to geographical background conditions, limiting the universality of prediction models when transferring them to different places. In this study, this article proposes a deep learning network designed to predict the spatiotemporal probability of rainfall-induced debris flows, incorporating the Similarity Mechanism of Debris Flow Critical Conditions (SM-DFCC). The model comprehensively integrates the mining of rainfall-triggering features and couples them with geographical background features to fit the nonlinear relationship with debris flow formation. The model underwent training using data on various historical debris flows triggered by different storms across Liangshan Prefecture from 2020 to 2022. The results indicated that: (i) the method is effective in predicting the spatiotemporal likelihood of debris flows under catchment units, with accuracy scores (ACC) ranging from 0.724 to 0.835; (ii) after optimization using the AVOA algorithm, the predictive performance of the model significantly improved, with an increase of 27.24% in ACC scores for SVC and 8.81% for XGBoost; and (iii) factor importance analysis revealed that rainfall triggering factors have higher cumulative contribution rates when distinguishing between the occurrence and non-occurrence of debris flows. In addition, taking a rainfall storm on 06, September 2020 as a case, this research quantitatively revealed the pattern of debris flow formation, where high-frequency disaster areas exhibit lower rainfall thresholds of debris flows, represented by absolute energy (AE). Despite these findings, the accuracy and reliability of rainfall data still remain the most challenging obstacle in basin/regional-scale debris flow prediction when applying this method. The integration of multiple sources of rainfall data, including station data, satellite rainfall, radar rainfall, etc., is necessary to accurately quantify the impact of rainfall on debris flow formation when applying this method to debris flow monitoring and early warning tasks. Overall, this method shows great potential in providing a scientific reference for the construction of debris flow monitoring and early warning systems in the future.

Navigating the ecosystem flood regulation service flows from subbasin to catchment in the Han River Basin

With the increasing cross-regional impact of climate change increasing in recent years, the Han River Basin, as a vital water resource supply and densely populated area in China, faces severe cross-regional flood threats and challenges. The systematic consideration of flood regulation throughout the entire upstream and downstream of the basin has become imminent. Our research aims to gain a deeper understanding of the ecosystem flood regulation service flows from upstream to downstream within subbasins and catchments scales of the Han River Basin. The results showed that the overflow path from upstream to downstream of the flood was basically consistent with the trend of the stream and the main tributaries of the Han River. It emerged that subbasins c, e, g, h and k were the key areas for the overall regulation of the upstream and downstream floods at subbasin scale. A total of 11 catchments overflow into their adjacent downstream catchments across the subbasins, a fact which is critical for catchment scale flood regulation. What’s more, there is evident interaction not only between adjacent subbasin and catchment units but also substantial exchange of service flows between non-adjacent units. Notably, catchment c’s flood regulation service flow was primarily contributed by its non-adjacent units. These findings not only contribute to filling the current knowledge gap in cross-watershed flood overflow and flood regulation service flows, but also provide support for the integrated response of upstream and downstream flood disaster risk management at the whole basin scale.

Watershed carbon yield derived from gauge observations and river network connectivity in the United States

River networks play a critical role in the global carbon cycle. Although global/continental scale riverine carbon cycle studies demonstrate the significance of rivers and streams for linking land and coastal regions, the lack of spatially distributed riverine carbon load data represents a gap for quantifying riverine carbon net gain or net loss in different regions, understanding mechanisms and factors that influence the riverine carbon cycle, and testing simulations of aquatic carbon cycle models at fine scales. Here, we (1) derive the riverine load of particulate organic carbon (POC) and dissolved organic carbon (DOC) for over 1,000 hydrologic stations across the Conterminous United States (CONUS) and (2) use the river network connectivity information for over 80,000 catchment units within the National Hydrography Dataset Plus (NHDPlus) to estimate riverine POC and DOC net gain or net loss for watersheds controlled between upstream-downstream hydrologic stations. The new riverine carbon load and watershed net gain/loss represent a unique contribution to support future studies for better understanding and quantification of riverine carbon cycles.

ENVIRONMENTAL SUSTAINABILITY ASSESSMENT OF A HIMALAYAN CATCHMENT WITH LAND COVER INDICES AND LST RELATIONSHIP USING PRINCIPAL COMPONENT ANALYSIS – A GEOSPATIAL APPROACH

Abstract. Environmental sustainability assessment is a crucial part of the management of natural resources. Remote Sensing based environmental land cover indices such as Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI), Normalized Difference Built-up Index (NDBI), Normalized Difference Moisture Index (NDMI), and its associated Land Surface Temperature (LST) are the major governing factors for the environmental processes that happen on the surface of the earth . These NDVI, NDWI, NDBI, NDMI, and LST are generated for 2020 using the Landsat satellite datasets. The process-based relationship among them is complex and involves various parameters but may be easily represented by multiple linear regression models. Principal Component Analysis (PCA) is one such type that efficiently handles and evaluates the contribution of each of these factors to each other based on the sampling units. The study area is the upper Ramganga catchment in the Indian Himalayas, consisting of 117 sub-catchments. These catchment units (samples) are entangled with these environmental factors. The results of the PCA reveal the relationship between each of the environmental factors and their priority. Based on the uncorrelated factors priority suggestion from the PCA, catchment units were classified as high, moderate, or low categories based on their dominance in the relationship among the factors. These spatial variations in the environmental factors can help to assess the sustainability of resources in the Himalayan catchment.

Catchment scale spatial distribution of soil enzyme activities in a mountainous German coniferous forest

Topography features within catchments influence soil properties, nutrient status, microbial dynamics and ultimately enzyme activities. Extracellular soil enzymes are essential for the decomposition of organic substrates and play a central role in global biogeochemical cycles. How topography and soil properties drive the spatial expression of enzyme activities at the catchment scale is still underexplored, especially in coniferous forest ecosystems. This study investigated the activity of four extracellular soil enzymes: β-glucosidase (β-glu), β-cellobiosidase (β-cello), acid phosphatase (pho) and leucine-aminopeptidase (l-leu) in Oh and Ah horizons of a (27 ha) mountainous coniferous forest catchment (Wüstebach, Eifel National Park, Germany). Spatial patterns and "hot spots" of activities of these four enzymes (involved in C-,N-, and P- cycling) were examined in connection to catchment units differing in slope, exposure and soil type (Cambisol vs. Gleysol), and multiple soil parameters (i.e., moisture content, pH, C, N, P, K, Fe, Mn content, C:N, C:P and N:P ratio). Catchment enzyme activities were overall, except for β-cello, significantly higher in the Oh than Ah horizon. Lower β-glu, and l-leu activities were found where more anaerobic soil conditions did occur, e.g., the river valleys (RV). Neither enhanced Oh horizon erosion on steeper Eastern (ES) and Northeastern (NES) slopes nor larger spatial soil nutrients heterogeneity on Northern (NS) and Western (WS) slopes, did significantly affect enzyme activity. Landscape topography did lead to a spatial variation of the activity of the four enzymes examined. The site-specific variation in C-cycling enzymes (β-glu and β-cello) was most marked at drier East, Northeast and Northern slopes, for P-cycling (pho) within the central wetter river valley but was for N-cycling (l-leu) enzyme activity more homogeneously distributed over the whole catchment. Overall, enzyme activities were strongly correlated to soil properties (especially soil moisture and organic carbon), but locations NS (Wüstebach source area) and RV (Wüstebach river flow path) showed less site-specific correlations. Further refinement of site-specific soil and external factors driving spatial distribution of enzyme activities at catchment scales and beyond will help to further tool up this research at larger spatial scales.

An Improved Framework of Marine Major Function-Oriented Zoning in Advancing Ecosystem-Based Management

Planning and zoning of marine areas is a common practice worldwide. In China, marine major function-oriented zoning (MMFOZ) is an effective geographical method for ensuring sustainable marine resource and ecosystems development; however, ecosystem-based management (EBM) has neither been considered in MMFOZ research nor in practice. Thus, the current MMFOZ evaluation system does not consider integration between the terrestrial and marine components, and the administrative boundaries are adopted as those of research areas and spatial zoning units. Here, an improved MMFOZ framework is presented through an ecosystem-based delimitation of the research area and subregions and a novel indicator system integrating land- and sea-based impacts, to assess and discriminate MMFOZ. A bay ecosystem and nearby land catchment units were selected as the research object. The results revealed two marine optimized development zones, one marine significant development zone, and six marine restricted development zones were divided, with areas of 358.11 km2 (24.63% of the total zoning area), 605.95 km2 (41.69%), and 489.54 km2 (33.68%), respectively. The improved MMFOZ framework coupled with EBM effectively addressed the limitations of marine spatial planning (MSP), while providing a new practical tool for a novel paradigm of sea governance based on an EBM–MSP coupling framework.

Output Characteristics of Nitrogen and Phosphorus from Non-Point Source Pollution of Typical Land Use in A Micro-Watershed in Hilly Red Soil Region

Scientific identification of runoff output characteristics of different land use patterns is the premise of controlling non-point source pollution in watersheds. The hydrology and output process of non-point source pollutants of forest, planting, and construction land with different rainfall characteristics were observed using a micro-watershed in a low mountain and hilly region of Southern China. The results showed that land use affected the hydrological characteristics and water quality processes of runoff. The characteristics of runoff generation time and cumulative rainfall under typical rainfall conditions were as follows:construction land(9 min, 2.0 mm), planting land(35 min, 11.4 mm), and forest land(108 min, 24 mm). There were significant differences in the three land use types in the pollution output process characteristics, such as pollutant concentration of total suspended matter(TSS), total nitrogen(TN) and phosphorus(TP), their components, N/P ratio change, and output intensity. Under typical rainfall, different land use types had similar pollution output stages, the mass concentrations of TSS, TN, and TP in the initial runoff were high, and then gradually stabilized. In addition, the first 30 min of the flow generation process contributed to the TSS, TN, and TP loads within the 23%-43% range. At the annual scale, there were significant differences between the contribution rate of each land use type to TN and TP load and ratio per unit area; the highest contribution to total pollution load was planting land(57% and 45%), while the highest in pollution load per unit area was construction land(9.50-12.50). The results also showed that the distribution of key non-point source areas had different spatial and temporal dynamics, which was comprehensively determined by the land use types in catchment units, the characteristics of annual rainfall, among other factors. With the increase in rainfall, the main contribution non-point source pollution in the micro-watershed changed from construction land to planting land. Targeted ecological interception strategies should be implemented based on the distribution characteristics of key source areas and characteristics of underlying surface runoff production process.

Exploring the Benefits of Small Catchments on Rural Spatial Governance in Wuling Mountain Area, China

China is facing an important period of rural governance innovation and restructuring of territorial spatial patterns. This paper selects catchments as the most closely related spatial units for rural industrial development and rural settlement activities, profoundly revealing the characteristics of transformational development and spatial governance in mountainous areas. To date, extensive literature in this area has produced a broad multidisciplinary consensus on catchment water and soil conservation and rural industry development; however, the interactive mechanism of ecological, social, and economic networks, and the characteristics behind small catchments which benefit from spatial governance, have never been analyzed and are relatively new to the sphere of rural governance. Our research argues the relative importance of multi-scale catchment units compared with traditional administrative village units in enhancing the organizational benefits of rural revitalization in terms of workforce, resources, and capital, using the case study of a catchment in the Wuling mountainous area. Our study presents a framework to explore the multi-dimensional governance experience of a small catchment in the Wuling mountainous area and proposes to integrate the resource endowment advantages of small catchments into rural industries development and transform the economic and social benefits contained in the ecological environment into multi-scale spatial benefits among farmers, villages, and the regional rural area. However, not all cases provide positive evidence. The overall development of a catchment is confronted with complex constraints, which are mainly related to the development stage and local historical and geographical factors. Furthermore, affected by the top-down “project-system” in the “poverty era”, the logic of “betting on the strong” and the single-centered logic of resource allocation at the grassroots level exacerbated the fragmentation of the mountainous area. Generally speaking, the catchment perspective promotes regional linkage development and multi-center governance modes and triggers multidisciplinary theoretical thinking to some extent. The catchment’s overall development helps play to the comparative advantage of mountainous areas and promotes endogenous sustainable development to a certain degree. However, the promotion of catchment governance in poverty-stricken mountainous areas is faced with a lack of financial foundation and needs support in order to break through the national system and local social constraints.

Research on Spatial Management of Water Environment in Chaoyang City

The research put forward the technical methods for dividing the water environment management units in Chaoyang City. Based on the river basin and the characteristics of urban drainage, the catchment units with "monitoring section-control and section-corresponding and land area" were constructed for the main rivers in Chaoyang City. The sensitive areas and fragile areas were identified based on the water environment control units. Pollutant discharge surveys on key water environment control units were conducted. And this paper calculated the water environment capacity, analysed the potential improvement of the water environment quality. Water environment management and control requirements were also proposed in this paper.

Source-to-sink analysis in an Eocene rifted lacustrine basin margin of western Shaleitian Uplift area, offshore Bohai Bay Basin, eastern China

During the Eocene, the western Shaleitian Uplift and its adjacent sags constituted a source-to-sink (S2S) system on an active lacustrine basin margin with a steeply dipping boundary fault. We integrated a range of data types with subsurface observations from the western offshore Bohai Bay Basin (OBBB) that allowed us to quantify the size and classification of catchment-fluvial segments, and analyze the sedimentary architecture and sediment fluxes of the proximal fan-delta system. We then discovered quantitative coupling relationships among the parameters of ancient source-to-sink segments. Results show that in the study area the bedrock of the western Shaleitian Uplift is composed of Proterozoic migmatized granites or granites. On the basis of paleogeomorphology reconstruction, we established classification standards for multi-scale catchment units, divided the provenance into four third-order catchment units, obtained quantitative parameters of the catchment-unit area (A), catchment relief (R), and total sediment discharge (Q s , calculated by BQART model) and then confirmed the scales and distribution (cross-sectional area, S cs ) of sediment-transport pathways. Furthermore, we analyzed tectonic subsidence, sediment-dispersal patterns, and sediment fluxes of fan-delta systems (Q f ) using seismic sedimentology in the third member of the Eocene Shahejie Formation (Es 3 ). Finally, we used quantitative, multivariate, statistical analysis of the parameters involved in the source-to-sink segments to (1) show the proportional range between total sediment fluxes of fan delta (Q f ) and sediment discharge (Q s ) from catchment (largest rate of Q f /Q s in the lower part of Es 3 , smallest rate of Q f /Q s in the middle part of Es 3 , and the range from 30% to 70%) and (2) arrange the mainly controlled parameters in terms of their importance (i.e., rate of tectonic subsidence, catchment area, catchment relief, and cross-sectional area of sediment-transport pathway are listed in order of importance). This study can provide an effective way of quantifying and ordering the parameters important in that controlling a complex ancient source-to-sink system, thus helping to achieve an understanding of the process of tectono-sedimentary evolution on a rifted, lacustrine-basin margin. • Divide the catchment segment into different orders and pick up the main parameters. • Indicate the sediment-dispersal patterns and sediment flux of fan-deltas in an active extensional setting. • Reveal the correlation and ordering of multiple important parameters of ancient source-to-sink in a rift basin margin.

Assessing the hydrological behaviour of large-scale potential green roofs retrofitting scenarios in Beijing

Although the study of hydrological performance of green roofs is of great significance to urban water security and sustainable development, large-scale roofs greening within a city range has not received sufficient attention. In this study, a typical urban area of 675 km2 within the fifth ring road of Beijing was chosen as a case study. The potential green roofs were defined before being identified from high resolution images. Under three retrofitting scenarios (100%, 50% and 20%) of extensive green roofs, the hydrological behaviour of potential green roofs was investigated at catchment units by employing the Soil Conservation Service Curve Number model. The behaviour was evaluated finally through two aspects of the runoff reduction effect and the flooding mitigation effect. According to this study, a 19.6% of the potential green roofs within the study area indicates a strong potential for the future greening. In the city scale, the average runoff reduction rates decrease from 9.38% to 6.13% with the increasing return period of rainfall events. Catchments in the core of northern city play key roles in reducing runoff, by more than 10% with the 100% implementation scenario. This study also showed that flooding in 13 of the 20 underpasses would have been avoided in the 7.21 Rainstorm if only 20% of the potential green roofs had been implemented. This study demonstrated a potentially positive hydrological behaviour contributed by roof greening in the future Beijing at a city scale, and effective runoff reduction can be achieved if only with a 50% greening of the potential green roofs. However, urban planners should take notice of the predicament that the deposit of high potential green roofs do not match spatially well to the severe flooding sites.

Zoning and Analysis of Control Units for Water Pollution Control in the Yangtze River Basin, China

In order to meet the needs of the control-unit-based water pollution prevention problem in China, we proposed a comprehensive control unit zoning method with the combined basic administrative region and objective watershed management. The method can effectively connect the natural characteristics of watershed water sources, three-level zoning of water resources, and comprehensively consider the pollution distribution, socio-economics and many other factors. The zoning process includes four steps: (1) Generate the multi-level hydrological unit; (2) Identify the multi-element water catchment units; (3) Obtain the control unit with the administrative boundary as the boundary; (4) Check and adjust the results to meet the actual needs. Based on this method, the Yangtze River Basin was divided into 568 control units with a total area of 1.91 million km2. These control units were used as the basic unit to analyze the water quality status and the results show that the upper reaches have good water quality, while the lower reaches have poor water quality and more serious water pollution. Our study helps the Ministry of Environmental Protection of China develop the list of control units that are needed to improve water quality during the “13th Five-Year Plan”, with a goal to provide technical support for control-unit-based water pollution prevention and control in the future.

O que são poços? um panorama das terminologias utilizadas para captações de águas subterrâneas

Os avanços dos estudos de hidrologia subterrânea muitas vezes deixam de lado alguns conceitos essenciais e básicos referentes à área de conhecimento. As unidades de captações de águas subterrâneas, também conhecidas como poços, recebem diversas denominações nos mais diversos estudos e pesquisas em regiões distintas. Palavras como artesiano, freático, dentre outras, correlatas com os estudos com águas subterrâneas, são muitas vezes utilizadas de forma errônea na literatura existente. A falta de uma padronização de termos pode gerar dificuldades na interpretação dos dados em determinadas situações por causa da diferenciação das linguagens e, consequentemente, falta de compatibilidade entre banco de dados. Este trabalho objetiva traçar um panorama das terminologias utilizadas para denominar as unidades de captação de águas subterrâneas e, com isso, gerar uma discussão sobre a uniformização de uma nomenclatura única. A metodologia adotada na execução deste estudo foi realizada basicamente através da análise de trabalhos anteriores. Foi verificado que o assunto da “falta de uma padronização” já foi abordado por outros pesquisadores, porém a ausência de uma nomenclatura específica para as unidades de captação de águas subterrâneas continua existindo.

Processes and Modeling of Initial Soil and Landscape Development: A Review

Core Ideas The dynamic initial development phase of landscapes requires a novel modeling approach. The approach needs to incorporate the key factors of initial ecohydrological processes. Key factors are: primary structure, erosion, deposition, crusting, plant succession. Ecohydrological functional units may be derived from modellng and observations. From their behavior, general conclusions may be drawn on early system evolution. The development pathway of a landscape depends to a degree on the initial spatial distributions of mineral and organic components. The interaction between structures and ecohydrological processes during the critical initial development period is scarcely understood and often difficult to observe. While viable modeling approaches exist for most aspects of initial development (e.g., landscape evolution, vegetation succession), a deeper understanding of the prevailing feedback mechanisms requires a comprehensive, integrated modeling approach. We present a review of the current literature regarding the description of initial structures, the state‐of‐the‐art of research on structure‐forming processes and their interaction with existing and newly emerging structures, as well as the corresponding modeling efforts. The most relevant aspects are (i) sediment translocation processes and initial evolution of topography, (ii) surface crusting, (iii) vegetation succession, and (iv) the evolution of the soil pore space. Based on existing conceptions for integrated modeling of the coevolution of structures and ecohydrological behavior, we outline an integrative modeling framework that is based on a three‐dimensional spatial structural model of initial sediment distributions, which can be used to: (i) analyze the spatiotemporal development dynamics depending on initial structures; and (ii) relate the simulated structural development to available observations of initial ecohydrological development. We discuss possible validation and generalization strategies of modeling results, and propose to define three‐dimensional spatial functional catchment units (process domains) characterized by specific structural dynamics and the dominant ecohydrological processes.

Marine Spatial Planning advancing the Ecosystem-Based Approach to coastal zone management: A review

Planning a sustainable future for coastal populations requires the effective implementation of ecosystem management frameworks that explicitly incorporate human activities. A coupled framework of the Ecosystem-Based Approach with Marine Spatial Planning has been discussed and promoted by coastal managers for more than a decade. The proposed framework supports a balanced approach between development needs and the natural environment. This paper presents a qualitative review of Marine Spatial Planning case studies to gain insights into methodological approaches that account for human systems as components of the coastal environment. A total of twelve Marine Spatial Planning case studies were evaluated. Their use and integration of the Ecosystem-Based framework was assessed through a linguistic scale linked to a score of fuzzy numbers. Two management issues of interest were highlighted: how social, economic and environmental values were integrated into the spatial planning analysis; and how cross-realm connectivity was addressed by planning teams. Although the majority of case studies claimed to use the Ecosystem-Based Approach as the guiding framework, mixed results were observed. Relevant features of the Ecosystem-Based Approach were rarely included; such as the standardization of pressures from human activities, the integration of frameworks to assess ecosystem services and the implementation of Precautionary and Adaptive Management approaches. Important knowledge gaps were observed with regards to the assessment of social values, including the lack of spatial representation of ‘social connections’ to the marine environment and the lack of economic estimates of non-market values. Terrestrial and catchment units were not included in the majority of case studies; however, water quality management was used as a key element for the consideration of transboundary impacts. This comparative study reveals major differences in how coastal managers understand and integrate Ecosystem-Based Approaches with Marine Spatial Planning.

Assessing the geoecological functions of the green infrastructure in cities of Canada

An assessment is made of the geoecological functions of the green infrastructure for the cities of Canada by using landscape-basin approach at three spatial levels: regional, intra-urban and local. The study revealed regional and functional differences in the green infrastructure of Vancouver, Toronto and Ottawa, and determined the quantitative relationships between territories that have biospheric, recreational, foodproducing and environment-regulation functions. It is shown that the general urban (average according to the spatial scale) level develops many important attributes of configuration of the green infrastructure which come to be intimately linked to the history and modern tendencies of urban development. It is established that for the intra-urban level (Toronto), the large-area elements have the functions of a stabilization of the environment and sustainment of biodiversity, whereas area-limited fragments most often serve as recreational places of the public nearest access. We calculated the proportion of the urban area corresponding to different (according to the functions of runoff formation) types of catchment units; almost one-third of the area is represented by catchment units with no permanent streams or with a transformed drainage system. It is found that the highest percentage of forest land corresponds to the downstream portions of river basins and to areas along valleys, whereas these indicators are much lower in the upstream regions and near drainage divides. It is established that there is almost no correlation between the size of the runoff cell and its percentage of forest land and the degree of development.

Estimating flood exposure potentials in Turkish catchments through index-based flood mapping

Flooding is widely believed to be the most common natural disaster in Europe, and the changing climatic conditions are estimated to increase its adverse impacts. Effective flood strategies require thorough consideration of the factors underlying the flood generation mechanism and a widened display of mitigation priorities for spatially exhaustive assessments. Flood potential maps generated herein for indicating potential flood areas prove to be among powerful tools for comprehensive flood assessments. In the presented study, a countrywide characterization is achieved in this context by analyzing catchment units, which constitute the river basin systems in Turkey, through a series of spatial indices adapted from different factors effective in flood generation. The study aims to contribute to depicting priorities for in-depth flood assessments and to the re-orientation of subsequent control measures. The flood potential maps obtained for river catchments and designating individual locations with comparably higher flood potentials are expected to set light to the selection of case studies for local flood research in Turkey while contributing to decision making and policy implementation on flood control at the macroscale.

Predicting hot-spots of land use changes in Italy by ensemble forecasting

In the context of environmental change projections at the regional level, not only the climate but also the land use plays a key role. The limited availability of historical information reduces the possibility to calibrate land use change (LUC) models. Even in case of successful calibration, using it both for diagnostic and prognostic studies does not guarantee the reliability of single future simulations. Through ensemble forecasting, useful LUC predictions are evaluable. In this work, after introducing a modified version of the well-assessed CLUE-S model, we present reasonable hot-spots of LUC in Italy for the end of 21st century, derived from the agreement of a 32 simulation ensemble performed alternating two choices for five model configurations or inputs: (1) two different climate projections (reflecting A2 and B2 emission scenarios by IPCC, respectively); (2) two different degrees (slight and strong) of demographic increase; (3) the conservation (or not) of protected areas; (4) the influence (or not) among adjacent land uses in determining their shift; and (5) the importance (or not) of past/recent LUC trends. Results, in terms of LUC hot-spot distribution, were evaluated at administrative, biogeographical, physiographic, and watershed level. The main findings highlighted that some trends of land use substitution will be likely opposite to the past and that a more detailed spatial scale can detect situations neglected by coarser scale evaluations, and due to different transpositions of directives from high-levels to local scales. Biogeographical and physiographic settings seem strongly influencing LUCs, and administrative and catchment units across Italy show very different developments and a highly fragmented territory in terms of LUC hot-spots, all that to be considered in landscape and resource planning.

A Paradigm Shift in Hydrology: Storage Thresholds Across Scales Influence Catchment Runoff Generation

AbstractA paradigm shift is occurring in the science surrounding runoff generation processes. Results of recent field investigations in landscapes and during periods previously unobservable are shaping new ideas on how runoff is generated and transferred from the hillslope to the catchment outlet. The previous paradigm saw runoff generation and contributing area variability as a continuum. The new paradigm is based not on continual storage satisfaction and runoff generation but threshold‐mediated, connectivity‐controlled processes dictated by heterogeneity in the catchment. This review focuses on the body of literature summarizing research on storage, storage thresholds and runoff generation, particularly over the last several years during which this paradigm shift has occurred. Storage thresholds that control the release of water exist at scales as small as the soil matrix and as large as the catchment. Hysteresis in storage–runoff relationships at all scales manifest because of these thresholds. Because storage thresholds at a range of scales have now been recognized as important, connectivity has become an important concept crucial to understanding how water is transferred through a catchment. This new paradigm requires basins to be instrumented within the context of a water budget investigation, with measurements taken within key catchment units, in order to be successful. New model approaches that incorporate connectivity are required to address the findings of field hydrologists. These steps are crucial if our community wishes to adopt the holisitic view of the catchment necessary to answer the questions posed to us by the society.

The catchment approach as the scientific basis of river basin management

Human impacts on river systems worldwide create a compelling case for effective river basin management. This paper examines the strengths and weaknesses of this approach and the role of science in underpinning it. There are many practical reasons for adopting integrated catchment management (ICM): achieving sustainable use of water resources demands a catchment approach to problems of water quality and quantity. Together with philosophical and economic arguments for nature conservation, and the legislative requirements laid down in the EC Water Framework Directive (WFD), the need for ICM is undeniable. In practice, however, ICM is hindered by significant gaps in scientific understanding. Some are geographical (e.g. inadequate knowledge of headwaters), some ecological (e.g. links between catchment processes, habitats, and aquatic species) while some relate to scale (e.g. extrapolating small-scale observations to entire catchments). The WFD is playing an increasing role in European river basin management, yet technical tasks such as defining 'reference conditions' or classifying 'ecological status' are hampered by inadequate scientific knowledge. It is essential that the results of scientific studies are made widely available, both through peer-reviewed publications and by conversion into practical guidelines or manuals for river engineers and managers. Although the river basin is a logical and defensible unit for conservation and management, the paper concludes that an even wider perspective is needed. Supra-catchment pressures from acid deposition or invasive alien species pose serious threats to rivers: efforts to tackle these issues cannot be confined to catchment units but must look out beyond the watershed.