Better understanding the hydrology of peri-urban ephemeral pools serving as habitats for the Western Chorus Frog

2020 ◽  
Author(s):  
Marie Larocque ◽  
Marjolaine Roux ◽  
Sylvain Gagné ◽  
Cousineau Olivier
Keyword(s):  
Reproductive Success ◽  
Human Impacts ◽  
Population Decline ◽  
Shallow Groundwater ◽  
Early Summer ◽  
Water Levels ◽  
Drainage Area ◽  
Groundwater Levels ◽  
Ephemeral Pools ◽  
Chorus Frog

<p>Ephemeral (vernal) pools are small hydrologically isolated wetlands found in a large variety of environments across the world. They provide breeding habitats for amphibians during their spring and early summer period of hydrological activity. Because of their small size and intermittent nature, many questions remain unanswered about their hydrology and concerning best strategies to improve their resilience to human activities and climate change. In the peri-urban area around Montreal City (Monteregie region, Quebec, Canada), ephemeral pools are habitats to the endangered Western Chorus Frog. In an attempt to protect the remaining population and to improve the reproductive success of these frogs, a study was funded by the Quebec Ministry of forest, fauna and parks to understand the processes driving pool hydrology and especially pool hydroperiod (length of hydrologically active period after snowmelt). Fourty-eight pools located in forested, agricultural and low-density housing developments were monitored for water levels since 2015. Seven of these pools were fully characterized for bathymetry and geology (field measurements), groundwater levels (hourly monitoring) and drainage area (LiDAR data). The pools are located on relatively flat land, in shallow irregular basins within generally low permeability Quaternary sediments. The pools hold relatively small volumes of water, with maximum annual water depths between 0.2 and 1.1 m (observed in April or May). Their areas vary between 100 and 5000 m<sup>2</sup>. The hydrologically active periods after snowmelt (starting after the last frost when mean temperature > 5°C over five days and ending when the pool is dry) vary between 15 and 150 days. At some sites, the hydroperiods were shorter than the required length for reproductive success of the Western Chorus Frog, which could explain the population decline. These short hydroperiods appear to be linked to the presence of human impacts in the pool vicinity. Water level reactions after precipitation are indications that pool hydrology is influenced by a relatively small contributing area rather than by their apparent drainage area (ratio Δh/rain < 4). Head gradients between water levels in the nearby sediments and pool water levels underline the role of the shallow groundwater in maintaining humid conditions in the pools and in reactivating the pools during the summer.  Simple water budget models  confirm this groundwater input and show that surface and hypodermic runoff is the main water source to the pools. The models show that, pool hydroperiods will start earlier under a changing climate, because of warmer winters, but will not necessarily be longer due to higher temperatures and increased evapotranspiration. The models will be used to estimate the effects of human interventions (e.g. drainage, residential) on pool hydroperiods, thus contributing to plan pool protection strategies that could help protect the Western Chorus Frog.</p>

The effects of fire on sulfidic peat swamp sediments

2020 ◽  
Author(s):  
Vanessa Wong ◽  
Tess Williamson ◽  
Barbara Etschmann ◽  
Sasha Wilson
Keyword(s):  
Mine Drainage ◽  
Shallow Groundwater ◽  
Water Levels ◽  
Decomposition Rates ◽  
Fire Hazards ◽  
Groundwater Levels ◽  
Peat Swamp ◽  
Increasing Temperature ◽  
Induced Changes ◽  
Underlying Soil

<p>Peat swamps contain substantial accumulations of organic matter due to waterlogging and slower decomposition rates. Peat swamps can be underlain by sulfidic sediments where there is  abundant iron and sulfate for reduction to form a range of sulfidic minerals, primarily pyrite (FeS<sub>2</sub>). Sulfidic sediments can acidify to produce sulfuric acid, similar to acid mine drainage (AMD) and acid sulfate soil (ASS) environments when oxidised, which can occur when water levels drop due to drainage or periods of drought. Discharging surface and shallow groundwater can therefore acidify adjacent lakes and waterways. These swamps can also present significant fire hazards when drying occurs. </p><p>This study identified the chemical and mineralogical changes in sulfidic peat swamp sediments along a temperature gradient to simulate the effects of fire. We found that fire induced changes in the Fe-minerals to form a range iron (oxy)hydroxides and iron oxides such as magnetite, mghemite and haematite in increasing crystallinity  with increasing temperatures. pH initially decreased on drying a minimum of pH 3.15, before increasing with increasing temperature to 650<sup>o</sup>C to pH 4.86, which can mobilise environmentally important pH-sensitive metals. </p><p>Peat swamps are highly susceptible to the effects of fire when surface- and shallow groundwater levels decrease as a result of extended drought or drainage. Fire can irreversibly alter underlying soil properties to induce changes in soil minerals and potentially impact the surrounding environment. </p>

scholarly journals Effects of soil texture and groundwater level on leaching of salt from saline fields in Kesem irrigation scheme, Ethiopia

2019 ◽  
Vol 14 (No. 4) ◽  
pp. 221-228
Author(s):  
Kidia K. Gelaye ◽  
Franz Zehetner ◽  
Willibald Loiskandl ◽  
Andreas Klik
Keyword(s):  
Soil Texture ◽  
Sandy Loam ◽  
Shallow Groundwater ◽  
Groundwater Table ◽  
Water Levels ◽  
Clay Loam ◽  
Irrigation Scheme ◽  
Groundwater Levels ◽  
Salinity Levels ◽  
Shallow Groundwater Table

In Ethiopia, soil salinity has become a challenge for agricultural production in irrigated arid and semi-arid areas. This research investigates the effectiveness of leaching salt remediation under different soil textures and groundwater tables. Leaching was conducted in the bare parts of three abandoned saline fields. Soil texture of Field 1 (F1) is sandy loam while Field 2 (F2) and Field 3 (F3) are clay loam. The F1, F2, and F3 groundwater was located at 1.8, 1.5 and > 3 m, respectively. The leaching requirement water levels were 15, 20, 25, and 30% higher than the evaporation of the bare field needed for four consecutive weeks, respectively. The results of this study show that, after four days of leaching, the salinity of F1 with sandy loam texture was significantly (P < 0.05) and more strongly reduced than for the other fields exhibiting clay loam texture. For F1, salinity was reduced from 16.3 to 6.2 dS/m and from 12.4 to 5.5 dS/m at depths of 0–30 and 30–60 cm, respectively. In head parts of F1 and F3, the salinity level was reduced to 2.0 dS/m. However, in F2 with shallow groundwater and clay loam texture, the salinity levels were slightly higher after leaching, i.e. from 11.2 to 12.0 dS/m and from 8.1 to 11.6 dS/m at 0–30 and 30–60 cm depths, respectively. In our experiment, effective leaching was achieved only in the field with sandy soil and deeper groundwater table. We saw that the application of leaching with surface drainage at shallow groundwater levels may further exacerbate salinity problems. For such situations, the use of subsurface drainage could sustain the groundwater depth and prevent additional salinization. On clay-textured fields with shallow groundwater table, a prolonged leaching application is necessary to reduce the salt contents.  

scholarly journals High-frequency monitoring of water fluxes and nutrient loads to assess the effects of controlled drainage on water storage and nutrient transport

2016 ◽  
Vol 20 (1) ◽  
pp. 347-358 ◽  
Author(s):  
J. C. Rozemeijer ◽  
A. Visser ◽  
W. Borren ◽  
M. Winegram ◽  
Y. van der Velde ◽  
...  
Keyword(s):  
Overland Flow ◽  
Shallow Groundwater ◽  
Early Spring ◽  
Water Levels ◽  
Passive Samplers ◽  
Small Scale ◽  
Nutrient Loads ◽  
Controlled Drainage ◽  
Groundwater Storage ◽  
Groundwater Levels

Abstract. High nitrogen (N) and phosphorus (P) fluxes from upstream agriculture threaten aquatic ecosystems in surface waters and estuaries, especially in areas characterized by high agricultural N and P inputs and densely drained catchments like the Netherlands. Controlled drainage has been recognized as an effective option to optimize soil moisture conditions for agriculture and to reduce unnecessary losses of fresh water and nutrients. This is achieved by introducing control structures with adjustable overflow levels into subsurface tube drain systems. A small-scale (1 ha) field experiment was designed to investigate the hydrological and chemical changes after introducing controlled drainage. Precipitation rates and the response of water tables and drain fluxes were measured in the periods before the introduction of controlled drainage (2007–2008) and after (2009–2011). For the N and P concentration measurements, auto-analyzers for continuous records were combined with passive samplers for time-averaged concentrations at individual drain outlets. The experimental setup enabled the quantification of changes in the water and solute balance after introducing controlled drainage. The results showed that introducing controlled drainage reduced the drain discharge and increased the groundwater storage in the field. To achieve this, the overflow levels have to be elevated in early spring, before the drain discharge stops due to dryer conditions and falling groundwater levels. The groundwater storage in the field would have been larger if the water levels in the adjacent ditch were controlled as well by an adjustable weir. The N concentrations and loads increased, which was largely related to elevated concentrations in one of the three monitored tube drains. The P loads via the tube drains reduced due to the reduction in discharge after introducing controlled drainage. However, this may be counteracted by the higher groundwater levels and the larger contribution of N- and P-rich shallow groundwater and overland flow to the surface water.

Flow directions of shallow groundwater in a boreal catchment

2021 ◽  
Author(s):  
Jana Erdbrügger ◽  
Ilja van Meerveld ◽  
Jan Seibert ◽  
Kevin Bishop
Keyword(s):  
Groundwater Flow ◽  
Surface Topography ◽  
Shallow Groundwater ◽  
Water Levels ◽  
Small Scale ◽  
Groundwater Levels ◽  
Dem Resolution ◽  
Elevation Data ◽  
Actual Flow ◽  
Flow Directions

<p>For most catchments, there is insufficient data to determine the location of the groundwater surface. For humid climates, it is, therefore, often assumed that the groundwater-surface follows the surface topography. This assumption allows using digital elevation models (DEMs) to estimate the flow directions and catchment boundaries. However, high-resolution elevation data also include many small-scale features that are unlikely to affect the direction of groundwater flow, or only affect it during specific conditions. Furthermore, flow directions may change during events or depending on the water level.</p><p>The optimal resolution of the DEM for determining groundwater flow directions is not known yet. Therefore, we studied how much DEM derived flow directions and catchment boundaries are affected by the resolution or smoothing of the elevation data for the Krycklan catchment in northern Sweden. We also measured the groundwater levels in two small sub-catchments to determine what DEM resolution best describes the actual groundwater-surface and flow directions.</p><p>For the topographic analyses, the LiDAR-based elevation data were first smoothed with various filters (e.g., Gaussian filters) and resampled to obtain lower resolution elevation data. We then determined the flow directions for these different DEMs. The aim was to determine where in the catchment the calculated flow directions are most sensitive to the resolution of the topographic data. The results of the topographic analyses show that for some areas, particularly flat areas, ridges, streambanks and locations where the local slope differs from the general slope, the calculated flow directions depend strongly on the resolution and smoothing of the elevation data.</p><p>To test how well the DEM based groundwater flow directions represent actual flow directions, we installed a dense (5-20 m spacing) network of shallow (1 to 6 m deep) groundwater wells (75 wells in total) in a 1 ha and a 2 ha gauged sub-catchment. The triangular nested design of the groundwater well network allowed us to determine the smaller (5 m) and larger scale (20 m) groundwater gradients. The recorded water levels were augmented and validated by manual measurements during the summers of 2018 and 2019. The high spatial and temporal resolution data allowed us to study the response of the groundwater level and the flow directions to different meteorological situations (e.g., large precipitation events after dry and wet conditions and during a very dry period in summer 2018). These observations indicate that the degree to which the groundwater-surface is a subdued copy of the surface topography varies throughout the year, and provides information on which DEM resolution most accurately represents the groundwater-surface and flow directions.</p>

Using groundwater levels and Specific Yield to Estimate the Recharge, South of Erbil, Kurdistan Region, Iraq

2018 ◽  
Vol 7 (4) ◽  
pp. 191
Author(s):  
Sherwan Sh. Qurtas
Keyword(s):  
Unconfined Aquifer ◽  
Middle Part ◽  
Water Levels ◽  
Specific Yield ◽  
Aquifer System ◽  
Groundwater Levels ◽  
Monitoring Wells ◽  
Water Table Fluctuation Method ◽  
Recharge Estimation ◽  
Fluctuation Method

Recharge estimation accurately is crucial to proper groundwater resource management, for the groundwater is dynamic and replenished natural resource. Usually recharge estimation depends on the; the water balance, water levels, and precipitation. This paper is studying the south-middle part of Erbil basin, with the majority of Quaternary sediments, the unconfined aquifer system is dominant, and the unsaturated zone is ranging from 15 to 50 meters, which groundwater levels response is moderate. The purpose of this study is quantification the natural recharge from precipitation. The water table fluctuation method is applied; using groundwater levels data of selected monitoring wells, neighboring meteorological station of the wells, and the specific yield of the aquifers. This method is widely used for its simplicity, scientific, realistic, and direct measurement. The accuracy depends on the how much the determination of specific yield is accurate, accuracy of the data, and the extrapolations of recession of groundwater levels curves of no rain periods. The normal annual precipitation there is 420 mm, the average recharge is 89 mm, and the average specific yield is around 0.03. The data of one water year of 2009 and 2010 has taken for some technical and accuracy reasons.

scholarly journals Seismically induced changes in groundwater levels and temperatures following the ML5.8 (ML5.1) Gyeongju earthquake in South Korea

2021 ◽  
Author(s):  
Soo-Hyoung Lee ◽  
Jae Min Lee ◽  
Sang-Ho Moon ◽  
Kyoochul Ha ◽  
Yongcheol Kim ◽  
...  
Keyword(s):  
South Korea ◽  
Groundwater Level ◽  
Seismic Waves ◽  
Groundwater Resources ◽  
Fluid Pressure ◽  
Water Levels ◽  
Aquifer System ◽  
Groundwater Levels ◽  
Monitoring Wells ◽  
Gyeongju Earthquake

AbstractHydrogeological responses to earthquakes such as changes in groundwater level, temperature, and chemistry, have been observed for several decades. This study examines behavior associated with ML 5.8 and ML 5.1 earthquakes that occurred on 12 September 2016 near Gyeongju, a city located on the southeast coast of the Korean peninsula. The ML 5.8 event stands as the largest recorded earthquake in South Korea since the advent of modern recording systems. There was considerable damage associated with the earthquakes and many aftershocks. Records from monitoring wells located about 135 km west of the epicenter displayed various patterns of change in both water level and temperature. There were transient-type, step-like-type (up and down), and persistent-type (rise and fall) changes in water levels. The water temperature changes were of transient, shift-change, and tendency-change types. Transient changes in the groundwater level and temperature were particularly well developed in monitoring wells installed along a major boundary fault that bisected the study area. These changes were interpreted as representing an aquifer system deformed by seismic waves. The various patterns in groundwater level and temperature, therefore, suggested that seismic waves impacted the fractured units through the reactivation of fractures, joints, and microcracks, which resulted from a pulse in fluid pressure. This study points to the value of long-term monitoring efforts, which in this case were able to provide detailed information needed to manage the groundwater resources in areas potentially affected by further earthquakes.

scholarly journals Breeding biology and post-fledging dispersal of red-crowned parakeets (Cyanoramphus novaezelandiae) translocated to a fenced mainland sanctuary

2021 ◽  
Author(s):  
◽  
Ellen Irwin
Keyword(s):  
Reproductive Success ◽  
Human Impacts ◽  
Release Site ◽  
Habitat Destruction ◽  
Breeding Biology ◽  
Food Sources ◽  
Lifetime Reproductive Success ◽  
Species Dispersal ◽  
Dispersal Patterns ◽  
Mammalian Predators

<p>With human impacts like habitat destruction and climate change contributing to range contractions in species, translocations stand out as an important tool for conserving species suffering from these effects. However, an understanding of the life history of many threatened species prior to translocation is often lacking, but critical for translocation success. For example, dispersal away from the release site—particularly when a protected release site is surrounded by unmanaged habitat—can result in translocation failure, and therefore successful translocation practice must include an understanding of a species’ dispersal patterns. I conducted a study examining the breeding biology and post-fledging dispersal of a population of red-crowned parakeets Cyanoramphus novaezelandiae), or kakariki, recently translocated to a mainland sanctuary in Wellington, New Zealand. The sanctuary, ZEALANDIA, is fenced to exclude invasive mammalian predators; however, birds can and do leave. Approximately one-third of juveniles that dispersed outside the sanctuary were killed by predators. Kakariki post-fledging dispersal was male-biased, possibly driven by inbreeding avoidance, and distance dispersed decreased with increasing body condition. Parental age may have also influenced offspring dispersal. In addition, I found that kakariki reproductive success may be affected by age, and estimated lifetime reproductive success was >30 fledglings by age five. Conservation initiatives could work on controlling predators in currently unprotected reserves and around food sources that kakariki targeted, particularly in summer and autumn when many plants are fruiting and recently fledged juveniles are more active. Future translocations should consider selecting younger birds to translocate to take advantage of their high lifetime reproductive success and therefore improve viability of populations.</p>

scholarly journals Shallow groundwater in sub-Saharan Africa: neglected opportunity for sustainable intensification of small-scale agriculture?

2016 ◽  
Author(s):  
John Gowing ◽  
Geoff Parkin ◽  
Nathan Forsythe ◽  
David Walker ◽  
Alemseged Tamiru Haile ◽  
...  
Keyword(s):  
Groundwater Resources ◽  
Climatic Variability ◽  
Shallow Groundwater ◽  
Sustainable Intensification ◽  
Sub Saharan Africa ◽  
Small Scale ◽  
Groundwater Levels ◽  
Sub Saharan ◽  
Small Scale Irrigation

Abstract. There is a need for an evidence-based approach to identify how best to support development of groundwater for small scale irrigation in sub-Saharan Africa (SSA). We argue that it is important to focus this effort on shallow groundwater resources which are most likely to be used by poor rural communities in SSA. However, it is important to consider constraints, since shallow groundwater resources are likely to be vulnerable to over-exploitation and climatic variability. We examine here the opportunities and constraints and draw upon evidence from Ethiopia. We present a methodology for assessing and interpreting available shallow groundwater resources and argue that participatory monitoring of local water resources is desirable and feasible. We consider possib le models for developing distributed small-scale irrigation and assess its technical feasibility. Because of power limits on water lifting and also because of available technology for well construction, groundwater at depths of 50 m or 60 m cannot be regarded as easily accessible for small-scale irrigation. We therefore adopt a working definition of shallow groundwater as < 20 m depth. This detailed case study in the Dangila woreda in Ethiopia explores the feasibility of exploiting shallow groundwater for small-scale irrigation over a range of rainfall conditions. Variability of rainfall over the study period (9 % to 96 % probability of non-exceedance) does not translate into equivalent variability in groundwater levels and river baseflow. Groundwater levels, monitored by local communities, persist into the dry season to at least the end of December in most shallow wells, indicating that groundwater is available for irrigation use after the cessation of the wet season. Arguments historically put forward against the promotion of groundwater use for agriculture in SSA on the basis that aquifers are unproductive and irrigation will have unacceptable impacts on wetlands and other groundwater-dependent ecosystems appear exaggerated. It would be unwise to generalise from this case study to the whole of SSA, but useful insights into the wider issues are revealed by the case study approach. We believe there is a case for arguing that shallow groundwater in sub-Saharan Africa represents a neglected opportunity for sustainable intensification of small-scale agriculture.

Subaqueous speleothems from the Flinders Ranges, South Australia, as palaeohydrological archives for the arid zone

2021 ◽  
Author(s):  
Calla Gould-Whaley ◽  
Russell Drysdale ◽  
Jan-Hendrick May ◽  
John Hellstrom ◽  
Hai Cheng ◽  
...  
Keyword(s):  
Arid Zone ◽  
Regional Climate ◽  
South Australia ◽  
Middle Latitude ◽  
Water Levels ◽  
Human Migration ◽  
Dispersal Patterns ◽  
Groundwater Levels ◽  
Flinders Ranges ◽  
Ecosystem Changes

&lt;p&gt;Australia is the driest continent outside of Antarctica yet relatively little is known about its long-term moisture history. Many local palaeoclimate archives suffer preservation problems, particularly in the arid centre of the continent, where weathering and erosion leave behind an incomplete record. In an attempt to redress the paucity of arid-zone palaeoclimate records, we investigate &amp;#8216;pendulites&amp;#8217;, subaqueous speleothems that grow episodically according to fluctuations in local groundwater levels. At Mairs Cave (central Flinders Ranges, South Australia), pendulites have formed around stalactites. During the first sustained episode of drowning, the stalactite is veneered by subaqueous calcite, sealing it and preventing further stalactitic growth after water levels fall. Once sealed, the pendulites only record periods of persistent drowning, assumed to correspond to major pluvial episodes.&lt;/p&gt;&lt;p&gt;Age data from two pendulite samples collected from close to the ceiling where the highest water levels have reached reveal two main groundwater &amp;#8216;high-stand&amp;#8217; phases centred on ~67 and ~48 ka, coincident with Southern Hemisphere summer insolation maxima. This suggests that precession-driven southward migration of the ITCZ resulted in regular and persistent incursions of tropical air masses to the central Flinders Ranges. Trace element, stable isotope and growth-rate changes reveal that these orbitally controlled growth intervals are superimposed by regional climate responses to Dansgaard-Oeschger and Heinrich events. The results from Mairs Cave shed new light on the moisture history of central Australia, in particular the competing influences of tropical and middle-latitude circulation systems. This provides a precisely dated regional palaeoclimate template for reconstructing ecosystem changes, understanding human migration/dispersal patterns of the first Australians, and the progressive demise of megafauna. We also highlight the utility of subaqueous speleothems more generally as important archives for investigating arid-zone palaeoclimate.&lt;/p&gt;

scholarly journals Groundwater recharge processes in an Asian mega-delta: hydrometric evidence from Bangladesh

2020 ◽  
Vol 28 (8) ◽  
pp. 2917-2932
Author(s):  
Sara Nowreen ◽  
R. G. Taylor ◽  
M. Shamsudduha ◽  
M. Salehin ◽  
A. Zahid ◽  
...  
Keyword(s):  
Groundwater Recharge ◽  
Conceptual Models ◽  
Shallow Groundwater ◽  
Depositional Environments ◽  
Series Data ◽  
Groundwater Depletion ◽  
Bengal Basin ◽  
River Channels ◽  
Groundwater Levels ◽  
Pleistocene Aquifer

AbstractGroundwater is used intensively in Asian mega-deltas yet the processes by which groundwater is replenished in these deltaic systems remain inadequately understood. Drawing insight from hourly monitoring of groundwater levels and rainfall in two contrasting settings, comprising permeable surficial deposits of Holocene age and Plio-Pleistocene terrace deposits, together with longer-term, lower-frequency records of groundwater levels, river stage, and rainfall from the Bengal Basin, conceptual models of recharge processes in these two depositional environments are developed. The representivity of these conceptual models across the Bengal Basin in Bangladesh is explored by way of statistical cluster analysis of groundwater-level time series data. Observational records reveal that both diffuse and focused recharge processes occur in Holocene deposits, whereas recharge in Plio-Pleistocene deposits is dominated by indirect leakage from river channels where incision has enabled a direct hydraulic connection between river channels and the Plio-Pleistocene aquifer underlying surficial clays. Seasonal cycles of recharge and discharge including the onset of dry-season groundwater-fed irrigation are well characterised by compiled observational records. Groundwater depletion, evident from declining groundwater levels with a diminished seasonality, is pronounced in Plio-Pleistocene environments where direct recharge is inhibited by the surficial clays. In contrast, intensive shallow groundwater abstraction in Holocene environments can enhance direct and indirect recharge via a more permeable surface geology. The vital contributions of indirect recharge of shallow groundwater identified in both depositional settings in the Bengal Basin highlight the critical limitation of using models that exclude this process in the estimation of groundwater recharge in Asian mega-deltas.

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