Determination and integration of appropriate spatial scales for river basin modelling

Many studies have assessed tree development beneath canopies in forest ecosystems, but results are seldom placed within the context of broad-scale biophysical factors. Mapped landscape characteristics for three watersheds, located within the Coeur d'Alene River basin in northern Idaho, were integrated to create a spatial hierarchy reflecting biophysical factors that influence western white pine (Pinus monticola Dougl. ex D. Don) development under a range of canopy openings. The hierarchy included canopy opening, landtype, geological feature, and weathering. Interactions and individual-scale contributions were identified using stepwise loglinear regression. The resulting models explained 68% of the variation for estimating western white pine basal diameter and 64% for estimating height. Interactions among spatial scales explained up to 13% of this variation and better described vegetation response than any single spatial scale. A hierarchical approach based on biophysical attributes is an excellent method for studying plant and environment interactions.

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Identification of Synchronicity in Deterministic Chaotic Attractors for the Downscaling Process in the Bogotá River Basin

10.5194/egusphere-egu21-14752 ◽

2021 ◽

Author(s):

Santiago Duarte ◽

Gerald Corzo ◽

Germán Santos

Keyword(s):

Time Series ◽

Time Delay ◽

River Basin ◽

Spatial Scales ◽

Climatic Variables ◽

Chaotic Attractors ◽

Multiple Attractors ◽

Nearest Neighbours ◽

Basin Scale ◽

Non Linear

Bogot&#225;&#8217;s River Basin, it&#8217;s an important basin in Cundinamarca, Colombia&#8217;s central region. Due to the complexity of the dynamical climatic system in tropical regions, can be difficult to predict and use the information of GCMs at the basin scale. This region is especially influenced by ENSO and non-linear climatic oscillation phenomena. Furthermore, considering that climatic processes are essentially non-linear and possibly chaotic, it may reduce the effectiveness of downscaling techniques in this region.&#160;In this study, we try to apply chaotic downscaling to see if we could identify synchronicity that will allow us to better predict. It was possible to identify clearly the best time aggregation that can capture at the best the maximum relations between the variables at different spatial scales. Aside this research proposes a new combination of multiple attractors. Few analyses have been made to evaluate the existence of synchronicity between two or more attractors. And less analysis has considered the chaotic behaviour in attractors derived from climatic time series at different spatial scales.&#160;Thus, we evaluate general synchronization between multiple attractors of various climate time series. The Mutual False Nearest Neighbours parameter (MFNN) is used to test the &#8220;Synchronicity Level&#8221; (existence of any type of synchronization) between two different attractors. Two climatic variables were selected for the analysis: Precipitation and Temperature. Likewise, two information sources are used: At the basin scale, local climatic-gauge stations with daily data and at global scale, the output of the MPI-ESM-MR model with a spatial resolution of 1.875&#176;x1.875&#176; for both climatic variables (1850-2005). In the downscaling process, two RCP (Representative Concentration Pathways)&#160; scenarios are used, RCP 4.5 and RCP 8.5.For the attractor&#8217;s reconstruction, the time-delay is obtained through the&#160; Autocorrelation and the Mutual Information functions. The False Nearest Neighbors method (FNN) allowed finding the embedding dimension to unfold the attractor. This information was used to identify deterministic chaos at different times (e.g. 1, 2, 3 and 5 days) and spatial scales using the Lyapunov exponents. These results were used to test the synchronicity between the various chaotic attractor&#8217;s sets using the MFNN method and time-delay relations. An optimization function was used to find the attractor&#8217;s distance relation that increases the synchronicity between the attractors.&#160; These results provided the potential of synchronicity in chaotic attractors to improve rainfall and temperature downscaling results at aggregated daily-time steps. Knowledge of loss information related to multiple reconstructed attractors can provide a better construction of downscaling models. This is new information for the downscaling process. Furthermore, synchronicity can improve the selection of neighbours for nearest-neighbours methods looking at the behaviour of synchronized attractors. This analysis can also allow the classification of unique patterns and relationships between climatic variables at different temporal and spatial scales.

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Evaluation and Hydrologic Validation of Three Satellite-Based Precipitation Products in the Upper Catchment of the Red River Basin, China

Remote Sensing ◽

10.3390/rs10121881 ◽

2018 ◽

Vol 10 (12) ◽

pp. 1881 ◽

Cited By ~ 7

Author(s):

Yueyuan Zhang ◽

Yungang Li ◽

Xuan Ji ◽

Xian Luo ◽

Xue Li

Keyword(s):

River Basin ◽

Southwest China ◽

Spatial Scales ◽

Red River ◽

Low Flow ◽

Efficiency Coefficient ◽

Monthly Streamflow ◽

Red River Basin ◽

Hydrological Applications ◽

Trmm 3B42

Satellite-based precipitation products (SPPs) provide alternative precipitation estimates that are especially useful for sparsely gauged and ungauged basins. However, high climate variability and extreme topography pose a challenge. In such regions, rigorous validation is necessary when using SPPs for hydrological applications. We evaluated the accuracy of three recent SPPs over the upper catchment of the Red River Basin, which is a mountain gorge region of southwest China that experiences a subtropical monsoon climate. The SPPs included the Tropical Rainfall Measuring Mission (TRMM) 3B42 V7 product, the Climate Prediction Center (CPC) Morphing Algorithm (CMORPH), the Bias-corrected product (CMORPH_CRT), and the Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN) Climate Data Record (PERSIANN_CDR) products. SPPs were compared with gauge rainfall from 1998 to 2010 at multiple temporal (daily, monthly) and spatial scales (grid, basin). The TRMM 3B42 product showed the best consistency with gauge observations, followed by CMORPH_CRT, and then PERSIANN_CDR. All three SPPs performed poorly when detecting the frequency of non-rain and light rain events (<1 mm); furthermore, they tended to overestimate moderate rainfall (1–25 mm) and underestimate heavy and hard rainfall (>25 mm). GR (Génie Rural) hydrological models were used to evaluate the utility of the three SPPs for daily and monthly streamflow simulation. Under Scenario I (gauge-calibrated parameters), CMORPH_CRT presented the best consistency with observed daily (Nash–Sutcliffe efficiency coefficient, or NSE = 0.73) and monthly (NSE = 0.82) streamflow. Under Scenario II (individual-calibrated parameters), SPP-driven simulations yielded satisfactory performances (NSE >0.63 for daily, NSE >0.79 for monthly); among them, TRMM 3B42 and CMORPH_CRT performed better than PERSIANN_CDR. SPP-forced simulations underestimated high flow (18.1–28.0%) and overestimated low flow (18.9–49.4%). TRMM 3B42 and CMORPH_CRT show potential for use in hydrological applications over poorly gauged and inaccessible transboundary river basins of Southwest China, particularly for monthly time intervals suitable for water resource management.

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Reconsidering the sediment connectivity and sediment transfer under the influence of hydraulic structures and coal mining in the Jiu river basin

10.5194/egusphere-egu21-15317 ◽

2021 ◽

Author(s):

Gabriela Adina Morosanu ◽

Marta Cristina Jurchescu

Keyword(s):

Coal Mining ◽

River Basin ◽

Spatial Scales ◽

Sediment Supply ◽

Anthropogenic Factors ◽

Hydraulic Structures ◽

Water Runoff ◽

Sediment Sources ◽

Sediment Transfer ◽

The Impact

The key to an efficient basin management, taking into account both the liquid (river water runoff and its quality) and the solid (sediment sources and delivery) components lies in the way we approach the complex problem of sediment-generating areas in a river basin. This complexity is manifested both through the primary geomorphological processes that contribute to the mobilization of significant amounts of alluvia from the slopes and along the river valleys, and the various environmental and anthropogenic factors that act as restrictors or catalysts of sediment transfer.In the present study, we aim to analyze the various categories of anthropogenic factors, operating at different spatial scales (local or at subcatchment/river sector level), which contribute, together with the intrinsic geomorphological potential, to the sediment supply or, conversely, to the inhibition of erosion, transport and accumulation processes.Tracking sediment mobilization, transfer, intermediate storage and final delivery in a lithologically and geomorphologically complex environment, such as the Jiu River Basin (10,070 km2), located in SW Romania, is a difficult task which can become even more challenging when we factor in the contribution of some additional elements of an anthropic nature. In our study area, represented by a Carpathian and Danubian river basin, some of the most significant issues impacting the research include, on the one hand, the existence of reservoirs and dams, the strengthening of anti-flood embankments or the presence of water diversions, to cite only hydrotechnical interventions, or the impact of coal mining on landforms, slope processes and sediment sources, on the other hand. &#160;All these factors can act locally or regionally and they can surpass the influence exerted by the natural factors, thus being responsible for the reduction, storage, or, on the contrary, for the acceleration of specific hydro-sedimentary fluxes on certain paths.In order to connect these two categories of potential factors regulating sediment generation and transfer, the methodological approach consists in evaluating the internal &#8211; geomorphic upstream-downstream connectivity in relation/contrast with the disruptive anthropogenic factors. The proposed workflow can be divided in two steps: 1) the identification of the upstream sediment generating areas which are most connected to the downstream delivery/ storage/ accumulation areas (river network and river mouth) by applying the connectivity index (IC) proposed by Cavalli et al. (2013); and 2) the evaluation of potential hotspot areas exhibiting the highest degree of connectivity, as seen through the lens of the additional coupling or decoupling effects induced by the anthropic activities specific to the Jiu river basin: hydraulic structures and coal mining.Outcome discussions will focus on mapping problematic sediment production, storage and transfer sectors, as evidenced by the impact of hydrotechnical works and artificial landforms from coal mining on the connectivity potential of the Jiu river basin.

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Impact of Landscape Attributes on Surface Water in the Tiber River Basin (Central Italy)

Proceedings ◽

10.3390/proceedings2019030011 ◽

2019 ◽

Vol 30 (1) ◽

pp. 11

Author(s):

Gozzi ◽

Dakos ◽

Trevisani ◽

Buccianti ◽

Graziano ◽

...

Keyword(s):

Surface Water ◽

Water Chemistry ◽

River Basin ◽

Spatial Scales ◽

Sampling Site ◽

Central Italy ◽

Geographical Information ◽

Major Influence ◽

Compositional Data Analysis ◽

Tiber River

River catchments are highly complex systems characterized by several properties such as self-organization, multi-scale variability, hydraulic and topographic gradients, patchiness and heterogeneity, resilience and a hierarchical structure. These features, coupled with several geomorphological, anthropogenic and climatic drivers, are expected to influence the surface water composition over different temporal and spatial scales. The knowledge of these complex interlinks plays a key role in both river basin management and predictability to potential pollution events. Nevertheless, due to the considerable amount of factors involved in the analysis, the unique combination of attributes characterizing each catchment and the lack of data at an adequate scale, it still remains unclear which of the environmental parameters have a major influence on the water chemistry. In this work, the hierarchy of the variability in the chemical composition of 160 water samples collected in 2017 throughout the Tiber River Basin, the largest catchment in Central Italy (17,156 km2), was explored. The results obtained by using advanced statistical methods, including the Compositional Data Analysis, highlighted different sources of variability linked to the geological (low variability) and anthropogenic origin (high variability) of the main solutes. Furthermore, for each sampling site, the corresponding watershed was calculated from the Digital Terrain Model using a Geographical Information System-based elaboration. The aim was to evaluate the relationships between the landscape morphological properties of the watersheds, such as elevation, drainage area, slope or other morphometric indexes and the physical-chemical parameters of the river waters on the basis of different geological and topographical settings of the basin. The outcomes proved to be particularly useful to discriminate between water chemistry mainly influenced by surface run-off processes and that affected by ground water circulation.

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Tropical rainfall trend and stationarity analysis

Water Science & Technology Water Supply ◽

10.2166/ws.2020.143 ◽

2020 ◽

Vol 20 (7) ◽

pp. 2471-2483

Author(s):

Chun Kang Ng ◽

Jing Lin Ng ◽

Yuk Feng Huang ◽

Yi Xun Tan ◽

Majid Mirzaei

Keyword(s):

Climate Change ◽

Trend Analysis ◽

River Basin ◽

Spatial Scales ◽

Kendall Test ◽

Temporal Analysis ◽

Northern Region ◽

Rainfall Series ◽

Kelantan River Basin ◽

Temporal And Spatial

Abstract Climate change is most likely to cause changes to the temporal and spatial variability of rainfall. A trend analysis to investigate the rainfall pattern can detect changes over temporal and spatial scales for a rainfall series. In this study, trend analysis using the Mann–Kendall test and Sen's slope estimator was conducted in the Kelantan River Basin, Malaysia. The Kwiatkowski–Phillips–Schmidt–Shin (KPSS) test was applied to evaluate the stationarity of the rainfall series. This basin annually faces onslaughts of varying year-end flooding conditions. The trend analysis was applied for monthly, seasonal and yearly rainfall series between 1989 and 2018. The temporal analysis results showed that both increasing and decreasing trends were detected for all rainfall series. The spatial analysis results indicated that the northern region of the Kelantan River Basin showed an increasing trend, whilst the southwest region showed a decreasing trend. It was found that almost all the rainfall series were stationary except at two rainfall stations during the Inter Monsoon 1, Inter Monsoon 2 and yearly rainfall series. Results obtained from this study can be used as reference for water resources planning and climate change assessment.

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Using natural strontium isotopic signatures as fish markers: methodology and application

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f00-206 ◽

2000 ◽

Vol 57 (11) ◽

pp. 2280-2292 ◽

Cited By ~ 159

Author(s):

Brian P Kennedy ◽

Joel D Blum ◽

Carol L Folt ◽

Keith H Nislow

Keyword(s):

River Basin ◽

Stream Water ◽

Spatial Scales ◽

Fish Tissue ◽

Isotopic Signature ◽

Food Sources ◽

Sr Isotopes ◽

Connecticut River ◽

Isotopic Signatures ◽

Calcified Tissues

To distinguish Atlantic salmon (Salmo salar) populations in tributaries of the Connecticut River, we studied the incorporation and stability of Sr isotopes in juvenile salmon. We established the geologic basis for unique isotopic signatures in 29 salmon sites. Stream-specific Sr isotopic ratios (87Sr/86Sr) were found in calcified tissues of salmon parr within 3 months of stocking. We found little seasonal variation in the Sr signatures of stream water or fish tissue. There were no significant differences among the Sr signatures of otoliths, scales, and vertebrae. For mature salmon raised under constant conditions, 70% of the Sr isotopic signature in calcified tissues was derived from food sources. We developed a criterion for identifying moving fish based upon the isotopic variability of genetically marked fish. Applying this criterion to our streams, 7% of the fish in our study had incorporated Sr from multiple streams. Strontium isotopes distinguished all 8 regions in the White River basin and 7 of the 10 regions in the West River basin. When watersheds are considered together, Sr isotopes differentiated 11 unique signatures from 18 regions. We conclude that Sr isotopes are an effective marking tool and discuss ways in which they can be combined with other marking techniques over larger spatial scales.

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