scholarly journals The impact of ditch blocking on the hydrological functioning of blanket peatlands

2016 ◽  
Vol 31 (3) ◽  
pp. 525-539 ◽  
Author(s):  
Joseph Holden ◽  
Sophie M. Green ◽  
Andy J. Baird ◽  
Richard P. Grayson ◽  
Gemma P. Dooling ◽  
...  
Keyword(s):  
Ditch Blocking ◽  
The Impact ◽  
Blanket Peatlands ◽  
Hydrological Functioning

Dynamic assessment of flood inundation based on a spatiotemporal hydrological model feed by a dynamic representation of human activities

2020 ◽  
Author(s):  
Kouadio Prudence Aka ◽  
Gerald A Corzo P ◽  
Koffi blaise  Yao
Keyword(s):  
Land Use ◽  
Human Activities ◽  
Historical Data ◽  
Morphometric Parameters ◽  
Climatic Data ◽  
Runoff Water ◽  
Dynamic Representation ◽  
The Impact ◽  
The City ◽  
Hydrological Functioning

<p>Floods are one of the most recurrent and damaging natural disasters in cities in developing countries today. The city of Abidjan (economic capital of Côte d'Ivoire) is not immune to these disasters. Indeed, according to the ONPC (2014), floods have killed an average of 13 people each year since 2009. One of the causes of the worsening and recurrence of these disasters is the urbanization experienced by the city of Abidjan in recent years. This urbanization has resulted in an increase in waterproofed areas and at the same time an increase in the volume of runoff water. The main objective of this research is to study the dynamics of floods and to see the impact of human activities on the hydrological functioning of the Gourou and Bonoumin watersheds in order to anticipate the risks of flooding. To do this, several specific objectives have been assigned in this study. These are: (1) the morphometric characterization of each watershed ; (2) the cartographic and diagnostic of stormwater management works and the dynamics of land use as well as the study of the variability of rainfall relative to the resurgence of floods in each basin ; (3) the establishment of a geographic information system for the study of floods; and (4) the prospective study of the evolution of land use and the future hydrological functioning of the watersheds studied using scenarios in order to take measures to fight against floods. The equipment used is composed of rain gauges (for measuring the spatial variation of rainfall in each sub-basin), limnimetric scales (to measure the heights of water in rivers), a double-ring infiltrometer (to measure the infiltration capacity on the basins) and software (Goldsim for simulating the behavior of watersheds). The data used consist of climatic data (temperature, rain), historical data on the floods in Abidjan, land use data (satellite images), physical characterization data of the watersheds (slope, hydrographic network, sanitation network , rainwater management works, morphometric parameters of the basins. The methodology adopted consisted of (1) collecting historical data on past floods in Abidjan; (2) description of the environment during rainy events; (3) studying the morphometric parameters of the watersheds studied and also (4) the study of the evolution of rainfall. Thus, the results obtained made it possible to show that the Gourou and Bonoumin basins cover respectively an area of 27.42 km² and 46.37 km² and the Gravelius indices of the two basins are respectively 4.89 and 5.51. Each year, the risk of a flood occurring is 75% with an average of more than 500 million property damage. The level reached in flooded areas of about 1 meter and according to historical data about inundations in Abidjan, on average 16 people lose their lives each year.</p>

scholarly journals Hydrological functioning of western African inland valleys explored with a critical zone model

2018 ◽  
Vol 22 (11) ◽  
pp. 5867-5888 ◽  
Author(s):  
Basile Hector ◽  
Jean-Martial Cohard ◽  
Luc Séguis ◽  
Sylvie Galle ◽  
Christophe Peugeot
Keyword(s):  
Land Cover ◽  
Hydrological Cycle ◽  
Water Storage ◽  
Critical Zone ◽  
Land Cover Changes ◽  
Zone Model ◽  
Water Budgets ◽  
Western Africa ◽  
The Impact ◽  
Hydrological Functioning

Abstract. Inland valleys are seasonally waterlogged headwater wetlands, widespread across western Africa. Their role in the hydrological cycle in the humid, hard-rock-dominated Sudanian savanna is not yet well understood. Thus, while in the region recurrent floods are a major issue, and hydropower has been recognized as an important development pathway, the scientific community lacks precise knowledge of streamflow (Q) generation processes and how they could be affected by the presence of inland valleys. Furthermore, inland valleys carry an important agronomic potential, and with the strong demographic rates of the region, they are highly subject to undergoing land cover changes. We address both the questions of the hydrological functioning of inland valleys in the Sudanian savanna of western Africa and the impact of land cover changes on these systems through deterministic sensitivity experiments using a physically based critical zone model (ParFlow-CLM) applied to a virtual generic catchment which comprises an inland valley. Model forcings are based on 20 years of data from the AMMA-CATCH observation service and parameters are evaluated against multiple field data (Q, evapotranspiration – ET –, soil moisture, water table levels, and water storage) acquired on a pilot elementary catchment. The hydrological model applied to the conceptual lithological/pedological model proposed in this study reproduces the main behaviours observed, which allowed those virtual experiments to be conducted. We found that yearly water budgets were highly sensitive to the vegetation distribution: average yearly ET for a tree-covered catchment (944 mm) exceeds that of herbaceous cover (791 mm). ET differences between the two covers vary between 12 % and 24 % of the precipitation of the year for the wettest and driest years, respectively. Consequently, the tree-covered catchment produces a yearly Q amount of 28 % lower on average as compared to a herbaceous-covered catchment, ranging from 20 % for the wettest year to 47 % for a dry year. Trees also buffer interannual variability in ET by 26 % (with respect to herbaceous). On the other hand, pedological features (presence – or absence – of the low-permeability layer commonly found below inland valleys, upstream and lateral contributive areas) had limited impact on yearly water budgets but marked consequences for intraseasonal hydrological processes (sustained/non-sustained baseflow in the dry season, catchment water storage redistribution). Therefore, subsurface features and vegetation cover of inland valleys have potentially significant impacts on downstream water-dependent ecosystems and water uses as hydropower generation, and should focus our attention.

scholarly journals Hydrological functioning of West-African inland valleys explored with a critical zone model

2018 ◽  
Author(s):  
Basile Hector ◽  
Jean-Martial Cohard ◽  
Luc Séguis ◽  
Sylvie Galle ◽  
Christophe Peugeot
Keyword(s):  
Land Cover ◽  
West Africa ◽  
Water Storage ◽  
Critical Zone ◽  
Land Cover Changes ◽  
Zone Model ◽  
Water Budgets ◽  
Inland Valley ◽  
The Impact ◽  
Hydrological Functioning

Abstract. Inland valleys are seasonally waterlogged headwater wetlands, widespread across West-Africa. Their role in the hydrological cycle in the humid, hard rock-dominated Sudanian area is not yet well understood. Thus, while in the region recurrent floods are a major issue, and hydropower has been recognized as an important development pathway, the scientific community lacks a precise knowledge of streamflow (Q) generation processes and how they could be affected by the presence of inland valleys. Furthermore, inland valleys carry an important agronomic potential, and with the strong demographic rates of the region, they are highly subjected to undergo land cover changes. We address both the questions of the hydrological functioning of inland valleys in the Sudanian area of West-Africa and the impact of land cover changes on these systems through deterministic sensitivity experiments using a physically-based critical zone model (ParFlow-CLM) applied on a synthetic catchment which comprises an inland valley. Model forcings are based on 20 years data from the AMMA-CATCH observation service and parameters are evaluated against multiple field data (Q, evapotranspiration – ET –, soil moisture, water table levels, and water storage). The hydrological model applied to the conceptual lithological/pedological model proposed in this study reproduces the main behaviors observed on a highly instrumented elementary catchment. We found that yearly water budgets were highly sensitive to the vegetation distribution: average yearly ET for a tree-covered catchment (944 mm) exceeds that of herbaceous-cover (791 mm). ET differences between the two covers vary between 12 and 24 % of the precipitation of the year for the wettest and driest year, respectively. As a consequence, the tree-covered catchment produces a yearly Q budget 28 % lower on average as compared to a herbaceous-covered catchment, ranging from 20 % for the wettest year to 47 % for a dry year. Trees also buffer interannual variability in ET by 26 %. On the other hand, pedological features (presence – or absence – of the low permeability layer commonly found below inland valley, upstream and lateral contributive areas) had limited impact on yearly water budgets but marked consequences on intraseasonal hydrological processes (sustained/unsustained baseflow in the dry season, catchment water storage redistribution ...). Therefore, subsurface features of inland valleys have potentially significant impacts on downstream water-dependent ecosystems and water uses as hydropower generation, and should focus our attention.

scholarly journals Quantifying the influence of surface water–groundwater interaction on nutrient flux in a lowland karst catchment

2016 ◽  
Vol 20 (5) ◽  
pp. 2119-2133 ◽  
Author(s):  
T. McCormack ◽  
O. Naughton ◽  
P. M. Johnston ◽  
L. W. Gill
Keyword(s):  
Surface Water ◽  
Hydrological Model ◽  
Nutrient Flux ◽  
Nutrient Loss ◽  
Nutrient Concentrations ◽  
Main Process ◽  
Stable Conditions ◽  
Karst Catchment ◽  
The Impact ◽  
Hydrological Functioning

Abstract. Nutrient contamination of surface waters and groundwaters is an issue of growing importance as the risks associated with agricultural run-off escalate due to increasing demands on global food production. In this study, the influence of surface water–groundwater interaction on the nutrient flux in a lowland karst catchment was investigated with the aid of alkalinity sampling and a hydrological model. The objective of the study was to determine the impact of ephemeral karst lakes (turloughs) on the surface water–groundwater nutrient flux, and whether these lakes act as sources or sinks of nutrients within the groundwater flow system. Water samples were tested from a variety of rivers, turloughs, boreholes and springs at monthly intervals over 3 years. Alkalinity sampling was used to elucidate the contrasting hydrological functioning between different turloughs. Such disparate hydrological functioning was further investigated with the aid of a hydrological model which allowed for an estimate of allogenically and autogenically derived nutrient loading into the karst system. The model also allowed for an investigation of mixing within the turloughs, comparing observed behaviours with the hypothetical conservative behaviour allowed for by the model. Within the turloughs, recorded nutrient concentrations were found to reduce over the flooded period, even though the turloughs hydrological functioning (and the hydrological model) suggested this would not occur under conservative conditions. As such, it was determined that nutrient loss processes were occurring within the system. Denitrification during stable flooded periods (typically 3–4 months per year) was deemed to be the main process reducing nitrogen concentrations within the turloughs, whereas phosphorus loss is thought to occur mostly via sedimentation and subsequent soil deposition. The results from this study suggest that, in stable conditions, ephemeral lakes can impart considerable nutrient losses on a karst groundwater system.

Modeling Hydrological Functioning of a Drainage Basin With Relation to Land Use Change in the Context of Climate Change

2019 ◽  
pp. 194-213
Author(s):  
Reda Rihane ◽  
Abdellatif Khattabi ◽  
Nabil Rifai ◽  
Said Lahssini
Keyword(s):  
Climate Change ◽  
Land Cover ◽  
Land Cover Change ◽  
Vegetation Cover ◽  
Drainage Basin ◽  
Forest Harvesting ◽  
Peak Flows ◽  
Water Flows ◽  
The Impact ◽  
Hydrological Functioning

Ourika basin in Morocco has very steep slopes with impermeable ground favoring water flows and flooding. History has shown deadly flood events. Floods are becoming recurrent and exacerbated not only by human activities that degrade soil and vegetation cover, accelerating erosion and quick water flows, but also by climate change. In fact, the basin has experienced a very strong dynamic of its vegetation cover, during the last 30 years, and has been subject to climate change impacts. This study is devoted to evaluating the impact of land cover change, mainly vegetation cover, on hydrological functioning of the basin. The HEC-HMS model was used to simulate basin hydrological response, according to two scenarios of land cover change. The first scenario simulates deforestation and urbanization impacts on peak flows, showing an increase of the peak flow by 31.68%. The second evaluates the impact of both reforestation actions and proscription of forest harvesting in the region. The simulated results showed a decline of 17.25% in peak flows, except for heavy precipitation events.

scholarly journals The impact of ditch blocking on fluvial carbon export from a UK blanket bog

2018 ◽  
Vol 32 (13) ◽  
pp. 2141-2154 ◽  
Author(s):  
Christopher D. Evans ◽  
Michael Peacock ◽  
Sophie M. Green ◽  
Joseph Holden ◽  
Pippa J. Chapman ◽  
...  
Keyword(s):  
Carbon Export ◽  
Blanket Bog ◽  
Ditch Blocking ◽  
The Impact

scholarly journals Hydrological Response of Natural Mediterranean Watersheds to Forest Fires

Hydrology ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. 15
Author(s):  
Konstantinos X. Soulis ◽  
Konstantina Amalia Generali ◽  
Christina Papadaki ◽  
Christos Theodoropoulos ◽  
Emmanouil Psomiadis
Keyword(s):  
Soil Properties ◽  
Forest Fires ◽  
Swat Model ◽  
Maximum Flow ◽  
Hydrological Balance ◽  
Depth Study ◽  
Considerable Impact ◽  
The Impact ◽  
Hydrological Functioning ◽  
Fire Conditions

Fires are common in forested Mediterranean-climate watersheds. Forest fires cause abrupt land use/cover (LULC) changes affecting soil properties and hydrological processes within and across watersheds. A major forest fire in Attica, Greece, that affected the Lykorrema stream experimental watershed provided the opportunity for an in-depth study of the impact of forest fires on the hydrological balance of natural Mediterranean watersheds. To this end, detailed hydrometeorological data recorded for five years before and for five years after the fire incidence were utilized. SWAT model was also used to consider the potential influence of meteorological conditions temporal variability on the results of the analysis. Specifically, SWAT model was parameterized calibrated and validated for the pre-fire and the post-fire conditions using the corresponding detailed hydrometeorological data for the respective periods. Then the two versions of the model were applied for the entire period providing comprehensive time series for all the flows and storages in the studied watershed. In this way, the post-fire LULC and soil properties changes were the only influencing factors driving the alterations in the hydrological balance allowing an impartial comparison. The obtained results highlighted the considerable impact of forest fires on the watersheds’ hydrological functioning. Specifically, the maximum direct runoff depths and the maximum flow rates were substantially higher in the post-fire conditions. In contrast, actual evapotranspiration was reduced, when the effect of fire was considered. The obtained results indicate that the altered post-fire LULC and soil properties are major drivers of the watershed’s hydrological balance changes. SWAT model performed sufficiently well for both the pre- and post-fire conditions and provided a deeper insight into the impact of forest fires on the hydrological functioning of natural Mediterranean watersheds.

Formation of Lunar Craters and Bright Rays as a Result of Meteorite Impacts

1962 ◽  
Vol 14 ◽  
pp. 415-418
Author(s):  
K. P. Stanyukovich ◽  
V. A. Bronshten
Keyword(s):  
Explosive Charge ◽  
The Moon ◽  
Meteorite Impacts ◽  
The Earth ◽  
Lunar Craters ◽  
The Impact

The phenomena accompanying the impact of large meteorites on the surface of the Moon or of the Earth can be examined on the basis of the theory of explosive phenomena if we assume that, instead of an exploding meteorite moving inside the rock, we have an explosive charge (equivalent in energy), situated at a certain distance under the surface.

The Geosciences Applied to Lunar Exploration

1962 ◽  
Vol 14 ◽  
pp. 169-257 ◽  
Author(s):  
J. Green
Keyword(s):  
Lunar Surface ◽  
Probable Mechanism ◽  
Point Of View ◽  
Lunar Exploration ◽  
Geological Model ◽  
Apply Geophysics ◽  
Surface Features ◽  
The Impact

The term geo-sciences has been used here to include the disciplines geology, geophysics and geochemistry. However, in order to apply geophysics and geochemistry effectively one must begin with a geological model. Therefore, the science of geology should be used as the basis for lunar exploration. From an astronomical point of view, a lunar terrain heavily impacted with meteors appears the more reasonable; although from a geological standpoint, volcanism seems the more probable mechanism. A surface liberally marked with volcanic features has been advocated by such geologists as Bülow, Dana, Suess, von Wolff, Shaler, Spurr, and Kuno. In this paper, both the impact and volcanic hypotheses are considered in the application of the geo-sciences to manned lunar exploration. However, more emphasis is placed on the volcanic, or more correctly the defluidization, hypothesis to account for lunar surface features.

Asteroid and Comet Impact Speeds upon Mars: Significance for Panspermia and the Supply of Organics

1997 ◽  
Vol 161 ◽  
pp. 197-201 ◽  
Author(s):  
Duncan Steel
Keyword(s):  
Probability Distributions ◽  
Regions Of Interest ◽  
Significant Fraction ◽  
Organic Chemicals ◽  
Impact Speed ◽  
The Mean ◽  
The Impact

AbstractWhilst lithopanspermia depends upon massive impacts occurring at a speed above some limit, the intact delivery of organic chemicals or other volatiles to a planet requires the impact speed to be below some other limit such that a significant fraction of that material escapes destruction. Thus the two opposite ends of the impact speed distributions are the regions of interest in the bioastronomical context, whereas much modelling work on impacts delivers, or makes use of, only the mean speed. Here the probability distributions of impact speeds upon Mars are calculated for (i) the orbital distribution of known asteroids; and (ii) the expected distribution of near-parabolic cometary orbits. It is found that cometary impacts are far more likely to eject rocks from Mars (over 99 percent of the cometary impacts are at speeds above 20 km/sec, but at most 5 percent of the asteroidal impacts); paradoxically, the objects impacting at speeds low enough to make organic/volatile survival possible (the asteroids) are those which are depleted in such species.

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