Hydrology of inland tropical lowlands: the Kapuas and Mahakam wetlands

Abstract. Wetlands are important reservoirs of water, carbon and biodiversity. They are typical landscapes of lowland regions that have high potential for water retention. However, the hydrology of these wetlands in tropical regions is often studied in isolation from the processes taking place at the catchment scale. Our main objective is to study the hydrological dynamics of one of the largest tropical rainforest regions on an island using a combination of satellite remote sensing and novel observations from dedicated field campaigns. This contribution offers a comprehensive analysis of the hydrological dynamics of two neighbouring poorly gauged tropical basins; the Kapuas basin (98 700 km2) in West Kalimantan and the Mahakam basin (77 100 km2) in East Kalimantan, Indonesia. Both basins are characterised by vast areas of inland lowlands. Hereby, we put specific emphasis on key hydrological variables and indicators such as discharge and flood extent. The hydroclimatological data described herein were obtained during fieldwork campaigns carried out in the Kapuas over the period 2013–2015 and in the Mahakam over the period 2008–2010. Additionally, we used the Tropical Rainfall Measuring Mission (TRMM) rainfall estimates over the period 1998–2015 to analyse the distribution of rainfall and the influence of El-Niño – Southern Oscillation. Flood occurrence maps were obtained from the analysis of the Phase Array type L-band Synthetic Aperture Radar (PALSAR) images from 2007 to 2010. Drought events were derived from time series of simulated groundwater recharge using time series of TRMM rainfall estimates, potential evapotranspiration estimates and the threshold level approach. The Kapuas and the Mahakam lake regions are vast reservoirs of water of about 1000 and 1500 km2 that can store as much as 3 and 6.5 billion m3 of water, respectively. These storage capacity values can be doubled considering the area of flooding under vegetation cover. Discharge time series show that backwater effects are highly influential in the wetland regions, which can be partly explained by inundation dynamics shown by flood occurrence maps obtained from PALSAR images. In contrast to their nature as wetlands, both lowland areas have frequent periods with low soil moisture conditions and low groundwater recharge. The Mahakam wetland area regularly exhibits low groundwater recharge, which may lead to prolonged drought events that can last up to 13 months. It appears that the Mahakam lowland is more vulnerable to hydrological drought, leading to more frequent fire occurrences than in the Kapuas basin.

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Hydrology of inland tropical lowlands: the Kapuas and Mahakam wetlands

10.5194/hess-2016-388 ◽

2016 ◽

Cited By ~ 1

Author(s):

H. Hidayat ◽

A. J. Teuling ◽

B. Vermeulen ◽

M. Taufik ◽

K. Kastner ◽

...

Keyword(s):

Time Series ◽

Groundwater Recharge ◽

Potential Evapotranspiration ◽

Southern Oscillation ◽

Tropical Rainfall Measuring Mission ◽

Threshold Level ◽

Phase Array ◽

Catchment Scale ◽

Tropical Regions ◽

Rainfall Estimates

Abstract. Wetlands are important reservoirs of water, carbon and biodiversity. They are typical landscapes of lowland regions that have high potential for water retention. However, the hydrology of these wetlands in tropical regions is often studied in isolation from the processes taking place at the catchment scale. This contribution offers a comprehensive analysis of the hydrological dynamics of two neighbouring poorly gauged tropical basins; the Kapuas basin (98,700 km2) in West Kalimantan and the Mahakam basin (77,100 km2) in East Kalimantan, Indonesia. Both basins are characterized by vast areas of inland lowlands. The hydro-climatological data described herein were obtained during fieldwork campaigns carried out in the Kapuas over the period 2013–2015 and in the Mahakam over the period 2008–2010. Additionally, we used the Tropical Rainfall Measuring Mission (TRMM) rainfall estimates over the period 1998–2015 for analysing the distribution of rainfall and the influence of El-Niño – Southern Oscillation. Flood occurrence maps were obtained from the analysis of the Phase Array L-band Synthetic Aperture Radar (PALSAR) images of 2007 through 2010. Drought events were derived from time-series of simulated groundwater recharge using time series of TRMM rainfall estimates, potential evapotranspiration estimates and the threshold level approach. The Kapuas and the Mahakam lakes region are vast reservoirs of water of about 1000 km2 and 1500 km2 that can store as much as 3 billion m3 and 6.5 billion m3 of water, respectively. These storage capacity values can be doubled considering the area of flooding under vegetation cover. Discharge time-series show that backwater effects are highly influential in the wetland regions, which can be partly explained by inundation dynamics shown by flood occurrence maps obtained from PALSAR images. In contrast to their nature as a wetland, both lowland areas have frequent periods with low soil moisture conditions and low groundwater recharge. The Mahakam wetland area regularly exhibits low groundwater recharges, which may lead to prolonged drought events that can last up to 13 months. It appears that the Mahakam lowland is more vulnerable to hydrological drought leading to fire occurrence than the Kapuas basin.

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Investigation of variable threshold level approaches for hydrological drought identification

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-11-12765-2014 ◽

2014 ◽

Vol 11 (11) ◽

pp. 12765-12797 ◽

Cited By ~ 20

Author(s):

B. S. Beyene ◽

A. F. Van Loon ◽

H. A. J. Van Lanen ◽

P. J. J. F. Torfs

Keyword(s):

Time Series ◽

Moving Average ◽

Threshold Level ◽

Snow Melt ◽

Rainfall Runoff ◽

Catchment Scale ◽

Climate Conditions ◽

Variable Threshold ◽

Rainfall Runoff Model ◽

Runoff Model

Abstract. Threshold level approaches are widely used to identify drought events in time series of hydrometeorological variables. However, the method used for calculating the threshold level can influence the quantification of drought events or even introduce artefact drought events. In this study, four methods of variable threshold calculation have been tested on catchment scale, namely (1) moving average of monthly quantile (M_MA), (2) moving average of daily quantile (D_MA), (3) thirty days moving window quantile (30D) and (4) fast Fourier transform of daily quantile (D_FF). The levels obtained by these methods were applied to hydrometeorological variables that were simulated with a semi-distributed conceptual rainfall-runoff model (HBV) for five European catchments with contrasting catchment properties and climate conditions. There are no physical arguments to prefer one method over the other for drought identification. The only way to investigate this is by applying the methods and visually inspecting the results. Therefore, drought statistics (i.e. number of droughts, mean duration, mean deficit) and time series plots were studied to compare drought propagation patterns determined by different threshold calculation methods. We found that all four approaches are sufficiently suitable to quantify drought propagation in contrasting catchments. Only the D_FF approach showed lower performance in two catchments. The 30D approach seems to be optimal in snow-dominated catchments, because it follows fast changes in discharge caused by snow melt more accurately. The proposed approaches can be successfully applied by water managers in regions where drought quantification and prediction are essential.

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Twelfth Century AD

10.1093/oso/9780199329199.003.0008 ◽

2017 ◽

Author(s):

Lonnie G. Thompson ◽

Alan L. Kolata

Keyword(s):

Climate Change ◽

Southern Oscillation ◽

Sediment Cores ◽

Critical Role ◽

Lake Titicaca ◽

Independent Evidence ◽

Tropical Regions ◽

Ice Cap ◽

Paleoclimate Records ◽

Past Climate Change

Climate is a fundamental and independent variable of human existence. Given that 50 percent of the Earth’s surface and much of its population exist between 30oN and 30oS, paleoenvironmental research in the Earth’s tropical regions is vital to our understanding of the world’s current and past climate change. Most of the solar energy that drives the climate system is absorbed in these regions. Paleoclimate records reveal that tropical processes, such as variations in the El Niño-Southern Oscillation (ENSO), have affected the climate over much of the planet. Climatic variations, particularly in precipitation and temperature, play a critical role in the adaptations of agrarian cultures located in zones of environmental sensitivity, such as those of the coastal deserts, highlands, and altiplano of the Andean region. Paleoclimate records from the Quelccaya ice cap (5670 masl) in highland Peru that extend back ~1800 years show good correlation between precipitation and the rise and fall of pre-Hispanic civilizations in western Peru and Bolivia. Sediment cores extracted from Lake Titicaca provide independent evidence of this correspondence with particular reference to the history of the pre-Hispanic Tiwanaku state centered in the Andean altiplano. Here we explore, in particular, the impacts of climate change on the development and ultimate dissolution of this altiplano state.

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The correlation between three teleconnections and leptospirosis incidence in the Kandy District, Sri Lanka, 2004–2019

Tropical Medicine and Health ◽

10.1186/s41182-021-00325-z ◽

2021 ◽

Vol 49 (1) ◽

Author(s):

N. D. B. Ehelepola ◽

Kusalika Ariyaratne ◽

A. M. S. M. C. M. Aththanayake ◽

Kamalanath Samarakoon ◽

H. M. Arjuna Thilakarathna

Keyword(s):

Time Series ◽

Sri Lanka ◽

Wavelet Analysis ◽

Southern Oscillation ◽

Population Data ◽

Enso Modoki ◽

Cross Correlation Analysis ◽

Teleconnection Indices ◽

Weather Parameters ◽

Time Lagged

Abstract Background Leptospirosis is a bacterial zoonosis. Leptospirosis incidence (LI) in Sri Lanka is high. Infected animals excrete leptospires into the environment via their urine. Survival of leptospires in the environment until they enter into a person and several other factors that influence leptospirosis transmission are dependent upon local weather. Past studies show that rainfall and other weather parameters are correlated with the LI in the Kandy district, Sri Lanka. El Niño Southern Oscillation (ENSO), ENSO Modoki, and the Indian Ocean Dipole (IOD) are teleconnections known to be modulating rainfall in Sri Lanka. There is a severe dearth of published studies on the correlations between indices of these teleconnections and LI. Methods We acquired the counts of leptospirosis cases notified and midyear estimated population data of the Kandy district from 2004 to 2019, respectively, from weekly epidemiology reports of the Ministry of Health and Department of Census and Statistics of Sri Lanka. We estimated weekly and monthly LI of Kandy. We obtained weekly and monthly teleconnection indices data for the same period from the National Oceanic and Atmospheric Administration (NOAA) of the USA and Japan Agency for Marine-Earth Science and Technology (JAMSTEC). We performed wavelet time series analysis to determine correlations with lag periods between teleconnection indices and LI time series. Then, we did time-lagged detrended cross-correlation analysis (DCCA) to verify wavelet analysis results and to find the magnitudes of the correlations detected. Results Wavelet analysis displayed indices of ENSO, IOD, and ENSO Modoki were correlated with the LI of Kandy with 1.9–11.5-month lags. Indices of ENSO showed two correlation patterns with Kandy LI. Time-lagged DCCA results show all indices of the three teleconnections studied were significantly correlated with the LI of Kandy with 2–5-month lag periods. Conclusions Results of the two analysis methods generally agree indicating that ENSO and IOD modulate LI in Kandy by modulating local rainfall and probably other weather parameters. We recommend further studies about the ENSO Modoki and LI correlation in Sri Lanka. Monitoring for extreme teleconnection events and enhancing preventive measures during lag periods can blunt LI peaks that may follow.

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Biomass Burning and Water Balance Dynamics in the Lake Chad Basin in Africa

Earth ◽

10.3390/earth2020020 ◽

2021 ◽

Vol 2 (2) ◽

pp. 340-356

Author(s):

Forrest W. Black ◽

Jejung Lee ◽

Charles M. Ichoku ◽

Luke Ellison ◽

Charles K. Gatebe ◽

...

Keyword(s):

Water Balance ◽

Biomass Burning ◽

Water Cycle ◽

Potential Evapotranspiration ◽

Southern Oscillation ◽

Wet Season ◽

Lake Chad ◽

Chad Basin ◽

Lake Chad Basin ◽

Logone Catchment

The present study investigated the effect of biomass burning on the water cycle using a case study of the Chari–Logone Catchment of the Lake Chad Basin (LCB). The Chari–Logone catchment was selected because it supplies over 90% of the water input to the lake, which is the largest basin in central Africa. Two water balance simulations, one considering burning and one without, were compared from the years 2003 to 2011. For a more comprehensive assessment of the effects of burning, albedo change, which has been shown to have a significant impact on a number of environmental factors, was used as a model input for calculating potential evapotranspiration (ET). Analysis of the burning scenario showed that burning grassland, which comprises almost 75% of the total Chari–Logone land cover, causes increased ET and runoff during the dry season (November–March). Recent studies have demonstrated that there is an increasing trend in the LCB of converting shrubland, grassland, and wetlands to cropland. This change from grassland to cropland has the potential to decrease the amount of water available to water bodies during the winter. All vegetative classes in a burning scenario showed a decrease in ET during the wet season. Although a decrease in annual precipitation in global circulation processes such as the El Niño Southern Oscillation would cause droughts and induce wildfires in the Sahel, the present study shows that a decrease in ET by the human-induced burning would cause a severe decrease in precipitation as well.

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Sensitivity of groundwater recharge using climatic analogues and HYDRUS-1D

Hydrology and Earth System Sciences ◽

10.5194/hess-16-2485-2012 ◽

2012 ◽

Vol 16 (8) ◽

pp. 2485-2497 ◽

Cited By ~ 35

Author(s):

B. Leterme ◽

D. Mallants ◽

D. Jacques

Keyword(s):

Water Balance ◽

Groundwater Recharge ◽

Potential Evapotranspiration ◽

Future Climate ◽

Annual Precipitation ◽

Balance Model ◽

Subtropical Climate ◽

Northern Spain ◽

Near Surface ◽

Hydrus 1D

Abstract. The sensitivity of groundwater recharge to different climate conditions was simulated using the approach of climatic analogue stations, i.e. stations presently experiencing climatic conditions corresponding to a possible future climate state. The study was conducted in the context of a safety assessment of a future near-surface disposal facility for low and intermediate level short-lived radioactive waste in Belgium; this includes estimation of groundwater recharge for the next millennia. Groundwater recharge was simulated using the Richards based soil water balance model HYDRUS-1D and meteorological time series from analogue stations. This study used four analogue stations for a warmer subtropical climate with changes of average annual precipitation and potential evapotranspiration from −42% to +5% and from +8% to +82%, respectively, compared to the present-day climate. Resulting water balance calculations yielded a change in groundwater recharge ranging from a decrease of 72% to an increase of 3% for the four different analogue stations. The Gijon analogue station (Northern Spain), considered as the most representative for the near future climate state in the study area, shows an increase of 3% of groundwater recharge for a 5% increase of annual precipitation. Calculations for a colder (tundra) climate showed a change in groundwater recharge ranging from a decrease of 97% to an increase of 32% for four different analogue stations, with an annual precipitation change from −69% to −14% compared to the present-day climate.

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Following the infection dynamics of the tropical trematode Oligogonotylus mayae in its intermediate and definitive hosts for 13 years

Journal of Helminthology ◽

10.1017/s0022149x20000875 ◽

2020 ◽

Vol 94 ◽

Author(s):

A.L. May-Tec ◽

N.A. Herrera-Castillo ◽

V.M. Vidal-Martínez ◽

M.L. Aguirre-Macedo

Keyword(s):

Time Series ◽

Cross Correlation ◽

Southern Oscillation ◽

Fish Host ◽

Snail Host ◽

Monthly Data ◽

Infection Dynamics ◽

Infection Parameters ◽

Over Time

Abstract We present a time series of 13 years (2003–2016) of continuous monthly data on the prevalence and mean abundance of the trematode Oligogonotylus mayae for all the hosts involved in its life cycle. We aimed to determine whether annual (or longer than annual) environmental fluctuations affect these infection parameters of O. mayae in its intermediate snail host Pyrgophorus coronatus, and its second and definitive fish host Mayaheros urophthalmus from the Celestun tropical coastal lagoon, Yucatan, Mexico. Fourier time series analysis was used to identify infection peaks over time, and cross-correlation among environmental forcings and infection parameters. Our results suggest that the transmission of O. mayae in all its hosts was influenced by the annual patterns of temperature, salinity and rainfall. However, there was a biannual accumulation of metacercarial stages of O. mayae in M. urophthalmus, apparently associated with the temporal range of the El Niño-Southern Oscillation (five years) and the recovery of the trematode population after a devasting hurricane. Taking O. mayae as an example of what could be happening to other trematodes, it is becoming clear that environmental forcings acting at long-term temporal scales affect the population dynamics of these parasites.

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Extracting the cumulative distribution location of highly intermittent river from Sentinel-1 time series in an alpine catchment on the Tibetan Plateau

10.5194/egusphere-egu21-4040 ◽

2021 ◽

Author(s):

Junyuan Fei ◽

Jintao Liu

Keyword(s):

Time Series ◽

Tibetan Plateau ◽

Time Scale ◽

Proper Time ◽

Cumulative Distribution ◽

The Tibetan Plateau ◽

Statistical Features ◽

Catchment Scale ◽

Intermittent Rivers ◽

Intermittent River

<p>Highly intermittent rivers are widespread on the Tibetan Plateau and deeply impact the ecological stability and social development downstream. Due to the highly intermittent rivers are small, seasonal variated and heavy cloud covered on the Tibetan Plateau, their distribution location is still unknown at catchment scale currently. To address these challenges, a new method is proposed for extracting the cumulative distribution location of highly intermittent river from Sentinel-1 time series in an alpine catchment on the Tibetan Plateau. The proposed method first determines the proper time scale of extracting highly intermittent river, based on which the statistical features are calculated to amplify the difference between land covers. Subsequently, the synoptic cumulative distribution location is extracted through Random Forest model using the statistical features above as explanatory variables. And the precise result is generated by combining the synoptic result with critical flow accumulation area. &#160;The highly intermittent river segments are derived and assessed in an alpine catchment of Lhasa River Basin. The results show that the the intra-annual time scale is sufficient for highly intermittent river extraction. And the proposed method can extract highly intermittent river cumulative distribution locations with total precision of 0.62, distance error median of 64.03 m, outperforming other existing river extraction method.</p>

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Improved representation of groundwater at a regional scale – coupling of mesocale Hydrologic Model (mHM) with OpeneGeoSys (OGS)

10.5194/gmd-2017-231 ◽

2017 ◽

Cited By ~ 2

Author(s):

Miao Jing ◽

Falk Heße ◽

Wenqing Wang ◽

Thomas Fischer ◽

Marc Walther ◽

...

Keyword(s):

Time Series ◽

Groundwater Flow ◽

Groundwater Recharge ◽

Large Scale ◽

Groundwater Modeling ◽

Coupled Model ◽

Hydrologic Model ◽

Source Modeling ◽

Prediction Ability ◽

Groundwater Head

Abstract. Most of the current large scale hydrological models do not contain a physically-based groundwater flow component. The main difficulties in large-scale groundwater modeling include the efficient representation of unsaturated zone flow, the characterization of dynamic groundwater-surface water interaction and the numerical stability while preserving complex physical processes and high resolution. To address these problems, we propose a highly-scalable coupled hydrologic and groundwater model (mHM#OGS) based on the integration of two open-source modeling codes: the mesoscale hydrologic Model (mHM) and the finite element simulator OpenGeoSys (OGS). mHM#OGS is coupled using a boundary condition-based coupling scheme that dynamically links the surface and subsurface parts. Nested time stepping allows smaller time steps for typically faster surface runoff routing in mHM and larger time steps for slower subsurface flow in OGS. mHM#OGS features the coupling interface which can transfer the groundwater recharge and river baseflow rate between mHM and OpenGeoSys. Verification of the coupled model was conducted using the time-series of observed streamflow and groundwater levels. Moreover, we force the transient model using groundwater recharge in two scenarios: (1) spatially variable recharge based on the mHM simulations, and (2) spatially homogeneous groundwater recharge. The modeling result in first scenario has a slightly higher correlation with groundwater head time-series, which further validates the plausibility of spatial groundwater recharge distribution calculated by mHM in the mesocale. The statistical analysis of model predictions shows a promising prediction ability of the model. The offline coupling method implemented here can reproduce reasonable groundwater head time series while keep a desired level of detail in the subsurface model structure with little surplus in computational cost. Our exemplary calculations show that the coupled model mHM#OGS can be a valuable tool to assess the effects of variability in land surface heterogeneity, meteorological, topographical forces and geological zonation on the groundwater flow dynamics.

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An Analysis of the Energetics of Tropical and Extra-Tropical Regions for Warm ENSO Composite Episodes

Revista Brasileira de Meteorologia ◽

10.1590/0102-778632120150114 ◽

2017 ◽

Vol 32 (1) ◽

pp. 39-51

Author(s):

Zayra Christine Sátyro ◽

José Veiga

Keyword(s):

Kinetic Energy ◽

Potential Energy ◽

El Niño ◽

Energy Production ◽

El Nino ◽

Southern Oscillation ◽

Stable Condition ◽

The Other ◽

Tropical Regions ◽

Using Data

Abstract This study focuses on the quantification and evaluation of the effects of ENSO (El Niño Southern Oscillation) warm phases, using a composite of five intense El Niño episodes between 1979 – 2011 on the Energetic Lorenz Cycle for four distinct regions around the globe: 80° S – 5° N (region 1), 50° S – 5° N (region 2), 30° S – 5° N (region 3), and 30° S – 30° N (region 4), using Data from NCEP reanalysis-II. Briefly, the results showed that zonal terms of potential energy and kinetic energy were intensified, except for region 1, where zonal kinetic energy weakened. Through the analysis of the period in which higher energy production is observed, a strong communication between the available zonal potential and the zonal kinetic energy reservoirs can be identified. This communication weakened the modes linked to eddies of potential energy and kinetic energy, as well as in the other two baroclinic conversions terms. Furthermore, the results indicate that for all the regions, the system itself works to regain its stable condition.

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