Increasing Hydroperiod in a Karst-depression Wetland Based on 165 Years of Simulated Daily Water Levels

Abstract

The hydrology of seasonally inundated depression wetlands can be highly sensitive to climatic fluctuations. Hydroperiod—the number of days per year that a wetland is inundated—is often of primary ecological importance in these systems and can vary interannually depending on climate conditions. In this study we re-examined an existing hydrologic model to simulate daily water levels in Sinking Pond, a 35-hectare seasonally inundated karst-depression wetland in Tennessee, USA. We recalibrated the model using 22 years of climate and water-level observations and used the recalibrated model to reconstruct (hindcast) daily water levels over a 165-year period from 1855 to 2019. A trend analysis of the climatic data and reconstructed water levels over the hindcasting period indicated substantial increases in pond hydroperiod over time, apparently related to increasing regional precipitation. Wetland hydroperiod increased on average by 5.9 days per decade between 1920 and 2019, with a breakpoint around the year 1970. Hydroperiod changes of this magnitude may have profound consequences for wetland ecology, such as a transition from a forested wetland to a mostly open-water pond at the Sinking Pond site. More broadly, this study illustrates the needs for robust hydrologic models of depression wetlands and for consideration of model transferability in time (i.e., hindcasting and forecasting) under non-stationary hydroclimatic conditions. As climate change is expected to influence water cycles, hydrologic processes, and wetland ecohydrology in the coming decades, hydrologic model projections may become increasingly important to detect, anticipate, and potentially mitigate ecological impacts in depression wetland ecosystems.

Projected Climate and Hydroregime Variability Constrain Ephemeral Wetland-Dependent Amphibian Populations in Simulations of Southern Toads

“…The hydroregime suitability projections used here were based on one of many climate models available and do not represent a guaranteed prognostication of future conditions; however, the impact of reduced precipitation represented by the CSIRO Mk3.5 A1B model used here was relatively minimal in comparison with other available models (e.g., MIROC3.2 A1B; [ 42 ]). Hydroregime changes in isolated groundwater-driven ephemeral wetlands will vary regionally, depending on the timing and amount of precipitation, existing groundwater levels prior to precipitation, geomorphology, and hydrologic processes [ 43 , 44 ]. Decreased hydroperiod during the BMP for southern toads or any ephemeral wetland-breeding amphibian is a concern, as fewer suitable wetlands for successful recruitment could result in increased isolation and reduced inter-wetland migration within a regional metapopulation.…”

Assessment of Huixian Karst Wetland for Local Water Augmentation in Guilin, China

“…As human activity, such as agricultural development and rapid urbanization, increases, wetlands get dwindled significantly each year and go through functional degradation on a global scale for a long time [4][5][6][7][8][9]. Especially karst wetlands with hydrological characteristics conditioned by karst terrains provide the key habitats for plants and animal species for local regional biodiversity [10][11][12][13]. Due to the characteristics of karst terrains, karst wetlands are also sensitive to climate change and global change [14][15][16][17].…”

Biodiversity and Litter Breakdown in a Karstic Freshwater System (Doberdò Lake, Northeast Italy) in Relation to Water Level Fluctuations and Environmental Features

“…Water level fluctuations represent a "pivotal disturbance factor", which is essential for the lake as it could also limit eutrophication [8,14]. However, climate change and human water use can cause changes in hydrological regimes, causing alterations in hydroperiod and seasonality: impacts can involve the shift in seasonal timing regarding the flood/drought cycle, changing the hydroperiod (duration of the wet period) [15,[50][51][52][53][54][55]. Karstic environments are particularly sensitive to these effects and the loss of seasonality could lead to alteration of ecosystem services [15].…”