Basin Morphometry Research Articles

Phragmites distribution relative to progressive water level decline in Lake Koronia, Greece

ABSTRACTLake Koronia is a hypertrophic Ramsar site in northern Greece. Water level dropped progressively from approximately 6 m in the mid‐1980s to 0·8 m in 2001 associated with over extraction of groundwater for agriculture, and the open water area has decreased from 4620 to 2930 ha, respectively. The resulting annual water level loss of 0·25–0·30 m year−1 was accompanied by expansion of Phragmites australis from a littoral fringe to dominance of exposed lake bottom areas from 97 ha in 1977 to 785 ha in 2005. The aim of this work was to apply an ecohydrological approach using remote sensing and geographic information system (GIS) to examine the movement of Phragmites relative to the water level retreat and to basin morphometry. Aerial expansion of Phragmites averaged 11–32 ha year−1 during the period of progressive water level decline but increased to 38–116 ha year−1 during a brief period of water level increase (2001–2003) as the plant colonized reflooded portions of the basin. The total area of Phragmites expanded 29% per annum during 1977–2005. Landward and lakeward margins of the Phragmites area followed water level retreat, moving 55 and 129 m, respectively, during the long period of progressive water level decline. Aerial movements of Phragmites in Lake Koronia are some of the highest reported in the literature. Mean water level within the Phragmites bed varied from 0·5 to 2·0 m during the period covered by this study. Very minor changes in basin slope, however, affected plant colonization rates, as evidenced by 200–250 ha/0·5 m water level drop at 0·18% basin slope to 360–1360 ha/0·5 m water level drop at 0·029% slope. The techniques applied to Lake Koronia for reconstructing past lake levels and associated distributions of Phragmites have broad application for understanding the dynamics of Phragmites elsewhere and anticipating periods of rapid plant expansion related to subtle changes in basin morphology. This study is useful for managing Phragmites populations in areas where efforts are being made to re‐establish populations as well as where elimination of invasive populations is sought. Copyright © 2013 John Wiley & Sons, Ltd.

Temporal and spatial variability of the internal wave field in a lake with complex morphometry

To quantify the effect of basin morphometry on internal wave dynamics, we installed thermistor arrays around the perimeter of Mono Lake, California. The lake's complex bathymetry includes alongshore bottom slopes ranging from < 1% up to 9% and a steep‐sided peninsula‐like island. Under the influence of the dominating winds from the south, isopycnals downwelled along the long axis of the lake as well as along an axis parallel to the peninsula, generating vertical mode 2 horizontal mode 2 internal waves. On relaxation of the wind, a horizontal mode 2 Kelvin wave evolved with a period of ∼ 22 h in each of the two sub‐basins. The response of the internal wave field to high winds was spatially variable, with higher vertical excursions of isopycnals and higher rates of strain, indicative of non‐linearity and turbulence, at both sides of the peninsula and near steep sloping boundaries to the south. Rate of strain squared was enhanced up to three orders of magnitude relative to background rates depending on bottom slope. Model comparisons in which the island was moved to the center of the lake or removed showed a dominant horizontal mode 1 wave and stronger influence of rotation. Increased complexity of basin morphometry modified the horizontal and vertical phase structure of dominant basin‐scale waves, redistributed the potential energy in the internal wave field over space, and shifted the positions of the basins in which the waves rotated. Whether turbulence increased with these shifts depended on the incidence of steep topography.

Water Regime of Playa Lakes from Southern Spain: Conditioning Factors and Hydrological Modeling

Andalusia's lowland countryside has a network of small geographically isolated playa lakes scattered across an area of 9000 km2 whose watersheds are mostly occupied by clayey rocks. The hydrological model proposed by the authors seeks to find equilibrium among usefulness, simplicity, and applicability to isolated playas in a semiarid context elsewhere. Based in such model, the authors have used monthly climatic data, water stage measurements, and the basin morphometry of a particular case (Los Jarales playa lake) to calibrate the soil water budget in the catchment and the water inputs from the watershed (runoff plus groundwater flow) at different scales, from monthly to daily. After the hydrologic model was calibrated, the authors implemented simulations with the goal of reproducing the past hydrological dynamics and forecasting water regime changes that would be caused by a modification of the wetland morphometry.

Application of Basin Morphometry Laws in catchments of the south-western quadrangle of south-eastern Nigeria

The relationship between process and form has been at the core of research in fluvial geomorphology. Form-process relationships of a natural river basin are strongly influenced by its hydrologic and sedimentologic processes as basin morphometric properties of length, shape, and relief, change in response to various hydrologic stimuli from the environment, but usually in line with well established laws. In the four river basins (Orashi, Otamiri, Sombreiro, New Calabar) examined in this study, however, empirical evidence does not conform neatly with theoretical postulates. Remarkable variations are noted in the morphometric properties of the catchments, when compared with established morphometric laws. The most varied in conformity are the Orashi and New Calabar basins, although the Sombreiro and Otamiri catchments also show some level of variation. Prime explanation for the morphometric and topographic non-conformity is caused by the nature of surficial material and the profoundly shallow relief of much of the study area, especially the alluvial flood and deltaic plains to the south and south-west of the study area.

Modeling the hydrologic effects of roadside ditch networks on receiving waters

Summary Roadside drainage networks can affect deleterious changes to watershed hydrology and water quality. However, very few studies have explored these effects in agricultural settings where the potential for nonpoint source pollution and the implications of tighter hydrologic linkages between landscape and stream are more critical. In this study, we apply a GIS-based, spatially distributed hydrologic model under a variety of drainage scenarios to quantify the hydrologic effects of roadside ditches at multiple spatial scales. We also qualitatively investigate the relative impacts of ditches on phosphorus transport. Our principle findings indicate that roadside ditches: (i) substantially alter basin morphometry and natural flow pathways, (ii) increase peak and total event discharge and (iii) expedite the transport of agricultural pollutants, thereby short-circuiting natural degradation processes that would otherwise have mitigated their effects. These findings underscore how relatively fine-scale alterations to natural flow pathways can result in substantial impacts to watershed scale hydrology and water quality and may help to inform spatially-targeted water resource management decisions and future modeling efforts.

Water exchange of three shallow Łęczna-Włodawa Lakes

AbstractThe research was carried out in three Łęczna-Włodawa lake-catchment systems, during the hydrological years 2007-2009. The observed lakes varied in terms of basin morphometry and catchment features. The hydrological functioning of the lakes resulted from three main factors: 1) storage capacity of the lake basin, 2) catchment area and relief, 3) human impact on water distribution. The vertical water exchange ratio in Lake Sumin was almost four-times higher than flushing time. In Lakes Rotcze and Syczyńskie horizontal water exchange, presented as flushing time was significantly higher than the vertical one.

Submerged aquatic vegetation in the Bay of Quinte: Response to decreased phosphorous loading and Zebra Mussel invasion

Originally mesotrophic, the Bay of Quinte ecosystem has experienced eutrophication since the 1940s, which resulted in the decline of once-lush submerged aquatic vegetation (SAV) beds in the upper bay by the mid-1960s. Since 1972, twelve SAV surveys have been conducted along ten index transects, recording:% cover, distance SAV beds extended from shore (extent), maximum depth of colonization (Zc), species composition, and, in later years, wet plant biomass. Offshore secchi depth and ϵpar, (the vertical light extinction rate (m−1) for photosynthetically active radiation), were also recorded either weekly or bi-weekly during the growing season since 1972. During this time, two major changes occurred within the bay: the reduction in point-source phosphorus (P-control) loadings in 1978 and the 1993 invasion by Dreissenid Mussel. SAV response to these changes varied temporally and spatially, with the shallow upper bay showing the greatest response, particularly after Zebra Mussels establishment. In the upper bay, mean secchi depth increased by 8% from 1.2 m prior to P-control (pre-P), to 1.3 m after P-control (post-P) and further increased by 46% to 1.9 m after Dreissena establishment (post-D). Upper bay SAV responded to these invasive species with increases in the means of three variables: Zc from 1.6 to 3.5 m, extent from 114 m to 417 m and wet biomass from 50 g m−2 to 962 g m−2. SAV in the middle and lower bays were in better condition in 1972, with pre-P cover in excess of 50% and Zc of 2.6 and 3.7 m, respectively. SAV cover did increase in the post-D (1994 to 2007) period by approximately 25% and Zc increased to 3.7 and 6.5 m, but the narrow fringing strip of shallower water along the shore in these two deeper bays limited substantial increases in bed extent. Both water clarity and basin morphometry strongly influenced SAV distribution and abundance within the Bay of Quinte.

Hydrological characterization of Mahd Ad Dahab Gold Mine, Saudi Arabia

The present study focuses on the gold mining in Mahd Ad Dahab region of Saudi Arabia. The study aims at the integrated use of existing meteorological information with the drainage basin morphometry of the mine catchment for determining the preferential flow path for the mine contaminants. The study reveals that the actual mining area lies at the headwaters of two watersheds: Watershed A and Watershed B. The streams in Watershed A drain in a North East - South West direction, whereas the streams of watershed B trend in a South East – North West direction. The peak runoff estimates show that in case of a heavy rainfall event, more surface discharge will be generated in Watershed A mainly due to its large surface area thus, leading to potential contamination in the south of the mining area. The runoff estimates for a maximum rainfall event of 104 mm/day is equal to 21.527 m3/s for Watershed A and 8.310 m3/s for Watershed B. Studies related to the investigation of the water pollution from mining activities should be concentrated towards the south of the mine. Key words: Mahd Ad Dahab Gold Mine, meteorology, drainage basin morphometry, runoff.

Geoinformatics for assessing the morphometric control on hydrological response at watershed scale in the Upper Indus Basin

Five watersheds (W1, W2, W3, W4 and W5) in the upper Indus basin were chosen for detailed studies to understand the influences of geomorphology, drainage basin morphometry and vegetation patterns on hydrology. From the morphometric analysis, it is evident that the hydrologic response of these watersheds changes significantly in response to spatial variations in morphometric parameters. Results indicate that W1, W2 and W5 contribute higher surface runoff than W3 and W4. Further, the topographic and land cover analyses reveal that W1, W2 and W5 generate quick runoff that may result in flooding over prolonged rainy spells. A physically based semi-distributed hydrologic model (soil and water assessment tool, SWAT) was used for simulating the hydrological response from the watersheds. As per the simulations, W5 watershed produces the highest runoff of 11.17 mm/year followed by W1 (7.9 mm/year), W2 (6.6 mm/year), W4 (5.33 mm/year) and W3 (4.29 mm/year). Thus, W5 is particularly more vulnerable to flooding during high rain spells followed by W1, W2, W4 and W3, respectively. Synthetic unit hydrograph analysis of the five watersheds also reveals high peak discharge for W5. The simulated results on the hydrological response from the five watersheds are quite in agreement with those of the morphometric, topographic, vegetation and unit hydrograph analyses. Therefore, it is quite evident that these factors have significant impact on the hydrological response from the watersheds and can be used to predict flood peaks, sediment yield and water discharge from the ungauged watersheds.

Hydrological impact of roadside ditches in an agricultural watershed in Central New York: implications for non‐point source pollutant transport

AbstractNonpoint source pollution and hydromodification are the leading causes of impairment to our nation's rivers and streams. Roadside ditch networks, ubiquitous in both rural and urban landscapes, intercept and shunt substantial quantities of overland runoff and shallow groundwater to stream systems. By altering natural flowpaths, road ditches contribute not only to hydromodification but also potentially to nonpoint‐source (NPS) pollution by acting as hydrological links between agricultural fields and natural streams. Unfortunately, the impacts of these alterations on watershed hydrology and water quality are not well understood. Through a series of field measurements, including field surveys and discharge monitoring, this study examined the effect of road ditch networks on basin morphometry, field‐ and watershed‐scale hydrology, and pollutant transport in a 38 km2agricultural watershed in south‐central NY. Salient findings include the following: (i) 94% of road ditches discharged to natural streams, effectively doubling the drainage density; (ii) on average, road ditches increased peak and total event flows in their receiving streams by 78% and 57%, respectively, but displayed significant variation across ditches; and (iii) ditches intercepted large quantities of surface and subsurface runoff from agricultural fields and therefore represent efficient conduits for the transport of agricultural NPS pollutants to sensitive receiving waterbodies. Our results provide useful information for hydrologists who wish to further understand how artificial drainage may be affecting watershed hydrology and for managers and engineers tasked with designing appropriate flood and NPS pollution control measures. Copyright © 2012 John Wiley & Sons, Ltd.

Preliminary Assessment of Mercury Accumulation in Massachusetts and Minnesota Seasonal Forest Pools

Seasonal forest pools (SFPs) are common, widespread, and provide critical habitat for amphibians and invertebrates. The ephemeral hydrology of SFPs has been identified as an important factor in the production of biologically active methylmercury (MeHg). To investigate mercury (Hg) in SFPs, we collected water, fine benthic organic matter (FBOM), detrital materials, and faunal samples from 10 pools in Massachusetts and Minnesota, across a range of basin morphometry, water chemistry, canopy closure, and hydroperiod. Total Hg (THg) and MeHg concentrations were comparable to other small, lentic waters. MeHg was found in greater concentrations in fauna than in periphyton, detrital items, or FBOM. In spite of consistently lower pool acidity and higher THg deposition in Massachusetts, we found no significant differences in Hg concentrations between states. No significant relationship was found between MeHg concentration and canopy closure. A weak, positive relationship was identified between pool hydroperiod and the bioaccumulation of THg, suggesting that longer exposure may be a factor in increased Hg concentrations in basal resources, which is then propagated into consumer trophic levels. Further work on the mechanisms determining Hg trophic transfer and bioaccumulation is required to fully understand the influence of hydrogeochemical and landscape influences on Hg dynamics in SFPs.

Kopalińskie Lake as an example of an anthropogenic reservoir of the southern Baltic Sea coast

Abstract The aim of this study is to discuss the water balance of Kopalińskie Lake, which is one of a few reservoirs on the Polish coast formed from anthropogenic activity. To realize this aim, lake basin morphometry and catchment hydrography were characterized. Moreover, the influence of the sea and the physico-chemical characteristics of the lake water were defined. As a result, the main characteristics of the lake and its catchment were found. Common characteristics of Kopalińskie Lake, as well as the characteristics that differentiate this reservoir from the other coastal lakes located on the Polish coast are presented in this work.

Landscape controls on total and methyl Hg in the upper Hudson River basin, New York, USA

Approaches are needed to better predict spatial variation in riverine Hg concentrations across heterogeneous landscapes that include mountains, wetlands, and open waters. We applied multivariate linear regression to determine the landscape factors and chemical variables that best account for the spatial variation of total Hg (THg) and methyl Hg (MeHg) concentrations in 27 sub‐basins across the 493 km2upper Hudson River basin in the Adirondack Mountains of New York. THg concentrations varied by sixfold, and those of MeHg by 40‐fold in synoptic samples collected at low‐to‐moderate flow, during spring and summer of 2006 and 2008. Bivariate linear regression relations of THg and MeHg concentrations with either percent wetland area or DOC concentrations were significant but could account for only about 1/3 of the variation in these Hg forms in summer. In contrast, multivariate linear regression relations that included metrics of (1) hydrogeomorphology, (2) riparian/wetland area, and (3) open water, explained about 66% to >90% of spatial variation in each Hg form in spring and summer samples. These metrics reflect the influence of basin morphometry and riparian soils on Hg source and transport, and the role of open water as a Hg sink. Multivariate models based solely on these landscape metrics generally accounted for as much or more of the variation in Hg concentrations than models based on chemical and physical metrics, and show great promise for identifying waters with expected high Hg concentrations in the Adirondack region and similar glaciated riverine ecosystems.

Temperature variability in the nearshore benthic boundary layer of Lake Opeongo is due to wind-driven upwelling events

A major source of temperature variation in nearshore and benthic regions of stratified lakes is due to wind-driven tilting of the thermocline. The maximum displacement of the thermocline depends upon the wind forcing, stratification, and basin morphometry; combined these three-dimensional physical parameters give the dimensionless lake number (LN). We find that the deflection of the thermocline across the length of the basin (Δh*) is correlated to the temporally averaged LN as Δh*/2h1 = 0.37LN–1, where h1 is the depth of the thermocline. We report field observations from Lake Opeongo (Ontario, Canada) showing that during large vertical movements of the thermocline, there are unstable temperature gradients in the benthic layer, as measured by the occurrence of temperature inversions on our thermistor strings. High-frequency waves interacting with the benthic boundary are most likely causing the temperature inversions. Measurements at two shallow slopes of S = 1% and 4%, show that inversions only occur when LN < 5, whereas for S = 8%, the inversions occur only when LN < 2.

Morphometric analysis of the drainage system and its hydrological implications in the rain shadow regions, Kerala, India

The rain shadow regions requisite a comprehensive watershed development and management plan for sustainable water resources management. The Pambar River Basin (PRB) lies on the rain shadow region of the southern Western Ghats, India, where climate showed marked intra-basin variation. A morphometric analysis was done to evaluate the drainage characteristics of PRB using topographical maps and digital elevation data. PRB was divided into eighteen 4th order basins (SB1-SB18), distributed along various climatic gradients. Lower order streams mostly dominate PRB and drainage pattern is a function of relief and structure. The terrain is highly dissected and prone to soil erosion during heavy storms and the elongated shape of PRB enables easier flood management. The influence of climate on drainage characteristics was evidently emphasized in basin morphometry. Four distinctively different classes were identified based on the morphometric similarities. The significance of morphometric analysis on the hydrological characterization is discussed and the relevance of the present study in water harvesting has been explicated.

Drainage basin morphometry: a global snapshot from the shuttle radar topography mission

Abstract. A suite of 42 morphometric parameters for each of 26 272 drainage basins larger than 100 km2 from the Hydrosheds Shuttle Radar Topography digital elevation model shows the global distribution of Strahler order for streams and drainage basins. At the scale of 15 arc s spacing (232 to 464 m) the largest basins are order 9. Many common parameters depend both on the size of the basin, and the scale of the digital elevation model used for the computations. These drainage basins display the typical longitudinal stream profiles, but the major basins tend to be generally more concave than the smaller basins.

Morphometric and chemical response of two contrasting lake systems to modern climate change

Observational data on the response of lakes during modern-day periods of abundant precipitation and drought may provide analogs for Holocene stratigraphic records and help elucidate the mechanisms that influence how lakes integrate climate. This study evaluated the impacts of climatic variation during the past 50 years on the morphometry and salinity of two neighboring lake systems in the central U.S. The two lakes were chosen, because paleolimnological reconstructions indicated that they had opposing geochemical responses to climate change at AD1200. This divergence suggested that local differences in hydrological setting had a major impact on the lake response to climate variation. Changes in surface area and volume were derived from aerial photographs and historic measurements of lake conductivity to contemporaneous annual precipitation data, the Palmer Drought Severity Index, and to groundwater table elevation. Hypsographic curves help to illustrate changes in lake surface area to depth. Both lakes showed predictable changes in surface area, volume, and salinity in response to precipitation change, but the magnitude of change in surface area and volume varied between the two lakes, likely because of differences in basin morphometry, but mechanisms remain speculative. These differences in basin size and shape also affected the salinity response over time. In the modern systems, the influence of groundwater on the chemical budgets appears to be limited and does not clarify the differential response of the lakes in the past. Yet, in the past the groundwater connection may have been different in turn changing the way the basins responded to climate. Although this study furthers our understanding of differences in the impacts of climate variations on Moon and Coldwater Lakes during recent times, it still does not clearly reveal why Moon and Coldwater Lake show opposite patterns of salinity change at 1200 A.D.

Drainage Basin Morphometry for Identifying Zones for Artificial Recharge: A Case Study from the Gagas River Basin, India

Abstract Drainage basin morphometry is a quantitative way of describing the characteristics of the surface form of a drainage basin and provides important information about the region’s topography and underlying geological structures. It plays an important role in hydrogeological investigations for delineating zones of adequate groundwater potential and selecting sites for construction of artificial recharge structures. In the present study an attempt was made to discover the stream properties in the Gagas River Basin of Almora district in the state of Uttarakhand using the various stream attributes. Based on the study the potential zones for the construction of artificial recharge structures in the basin were identified.

Modern non-pollen palynomorphs from East African lake sediments

This paper presents an illustrated guide to the identification of non-pollen palynomorphs (NPPs) preserved in lake-sediment archives from equatorial East Africa. Modern NPPs were recovered from recently deposited surface sediment in 20 small crater lakes in western Uganda, located along environmental gradients of vegetation (moist evergreen and semi-deciduous forest, wooded and open grass savannah), land use (pastoralism, crop agriculture, plantations) and lake characteristics (basin morphometry, water chemistry and aquatic production). We analyzed 9700 NPP specimens, which could be assigned to 265 distinct morphotypes, of which 239 belong to six major taxonomic groups: spores and other remains of fungi (198 morphotypes), spores of ferns and mosses (19 morphotypes), microscopic zoological remains (14 morphotypes), colonies, coenobia or zygo-/aplanospores produced by filamentous algae (7 morphotypes) and microscopic aquatic plant remains (1 morphotype). The remaining 26 morphotypes could not be assigned to a specific taxonomic category. Using primary taxonomic and molecular phylogenetic literature, 73 (28%) of the recovered morphotypes could be identified at the species, genus or family level, thereby conferring ecological indicator value to them. This study may facilitate the use of fossil NPPs to help reconstruct past climatic and anthropogenic impacts on African ecosystems, as already broadly established in other study regions outside Africa.

A method for flood hazard mapping based on basin morphometry: application in two catchments in Greece

Basin morphometric parameters play an important role in hydrological processes, as they largely control a catchment’s hydrologic response. Their analysis becomes even more significant when studying runoff reaction to intense rainfall, especially in the case of ungauged, flash flood prone basins. Unit hydrographs are one of the useful tools for estimating runoff when instrumental data are inadequate. In this work, instantaneous unit hydrographs based on the time-area method have been compiled along the drainage networks of two small rural catchments in Greece, situated approximately 25 km northeast of its capital, Athens. The two catchments drained by ephemeral torrents, namely Rapentosa and Charadros, have been subject to flash flooding during the last decades, which caused extensive damages at the local small towns of Marathon and Vranas. Hydrograph compilation in numerous locations along the catchments’ drainage networks directly reflected the runoff conditions across each basin against a given rainfall. This gave a holistic assessment of their hydrologic response, allowing the detection of areas where peak flow rates were elevated and therefore, there was higher flood potential. The resulting flood hazard zonation showed good correlation with locations of damages induced by past flood events, indicating that the method can successfully predict flood hazard spatial distribution. The whole methodology was based on geographic information software due to its excellent capabilities on storing and processing spatial data.