Impact of forest degradation on streamflow regime and runoff response to rainfall in the Garhwal Himalaya, Northwest India

Qazi, Nuzhat Q.; Bruijnzeel, L. A.; Prakash, Shive; Ghimire, Chandra Prasad

doi:10.1080/02626667.2017.1308637

Cited by 43 publications

(25 citation statements)

References 56 publications

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“…Across the world, studies in the Himalayas, the Western Ghats, and tropical Africa, have largely documented positive effects of forest cover on stream flow (e.g. Bonell et al, ; Ghimire, Bruijnzeel, Lubczynski, & Bonell, ; Krishnaswamy et al, ; Qazi, Bruijnzeel, Rai, & Ghimire, ; Recha et al, ). In Latin America and the Caribbean, there exists high diversity in hydro‐climatic, geomorphological, soil, and biological factors.…”

Section: Introductionmentioning

confidence: 99%

Positive and neutral effects of forest cover on dry‐season stream flow in Costa Rica identified from Bayesian regression models with informative prior distributions

Krishnaswamy

Kelkar

Birkel

2018

Hydrological Processes

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The influence of forest cover on dry-season stream flow in the humid tropics has been of enduring interest to eco-hydrologists and policy makers. We used data from eight nested gauging stations in the Terraba river basin (4774 km 2 ) of Costa Rica to demonstrate how a Bayesian regression approach could be applied to test hypotheses on "infiltration-evapotranspiration trade-offs", between the "sponge effect" and evapotranspiration demands of forests on dry-season flows. We summarized three competing hypotheses as informative prior distributions for regression slopes as 1) positive, 2) zero, and 3) negative effect of forest cover, and combined them with dry-season flow data (response), and annual rainfall and per cent forest cover (as covariates) to obtain posterior estimates. The time series included a deforestation phase until the 1980s and subsequent forest recovery from the 1990s. The sign, magnitude, and uncertainty of posterior slopes showed that forest cover effects on dry-season flow were generally positive or neutral, influenced by both forest loss and recovery. Forest cover effect on dry-season flow for the entire basin was strongly positive. Four sub-catchments showed weakly positive and two showed neutral effects, and only one indicated a weakly negative effect. Mean effect size of forest cover diminished with increase in basin size. Our results predict a gain of 3.3 mm in dry-season flow for every 1% increase of forest cover, corresponding to 48 km 2 of basin area. Enhanced infiltration and wet-season groundwater recharge dominating evapotranspiration can be attributed partly to deep soils and cloud forests. We demonstrate how informative prior distributions can represent different hypotheses in Bayesian regression models offers advantages in investigating complex hydrological processes. The rigorous evidence for positive and neutral effects of forest cover on dry-season flow, reported by our study, potentially contributes to ecohydrology-based management of tropical landscapes undergoing rapid change.

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Section: Introductionmentioning

confidence: 99%

Positive and neutral effects of forest cover on dry‐season stream flow in Costa Rica identified from Bayesian regression models with informative prior distributions

Krishnaswamy

Kelkar

Birkel

2018

Hydrological Processes

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“…These enhanced values indicated potential for soil water storage at forested catchment (Arnigad) and release the water slowly during the subsequent dry-period, which consequently helps in regulation of sustained stream ows in the Himalayan region. This can be further supported by the Figure 12, which shows that Arnigad had higher OM (21-89%) and higher porosity (3-11%) than Bansigad which helps Arnigad in retaining SM and upholding sponge characteristics (Qazi et al 2017). The lowest values of volumetric SM (mean monthly) were recorded as 25% (Arnigad) and 21% (Bansigad), indicating low (19%) storage de cit at Bansigad relative to Arnigad.…”

Section: Soil Moisture Variation At Different Soil Pro Lesmentioning

confidence: 60%

Hydrological Functioning of Forested Catchments, Central Himalayan Region, India.

Nuq¹

2020

Preprint

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Background: Central Himalayan forested catchments provide fresh water supply and innumerable ecosystem services to millions of people. Hence, the understanding of linkages between forests and water is very crucial to recognize for availability and quality of water at catchment scale. Therefore, present study aims to understand hydrological response of two forested catchments (namely, Arnigad and Bansigad) in the Central Himalayan Region.Methods: Three-year data (March, 2008 to February, 2011) were collected from meteorological and hydrological stations installed at Arnigad and Bansigad catchments. The present paper displays mean hydrological response of forested catchments through detailed field investigation.Results : The annual hyetograph analysis revealed that the rainfall at both the catchments was highly seasonal, and wet-period (June-September) plays a key role in catchment functioning. Exceedance of rainfall threshold of ~200 mm (~10% of annual rainfall) significantly increased streamflow generation at both the catchments. At Arnigad, stream was perennial with a mean baseflow of ~83 mm per month (~ 6 % of annual baseflow) whereas, Bansigad had greater seasonality due to lack of streamflow during the pre-wet-period (March-May). Separation of hydrographs at Arnigad and Bansigad catchments i.e. stormflow (6% and 31%, respectively) and baseflow (50% and 32%, respectively) helped to understand the probability of flooding during wet-period and drought during dry-period. Forest ecosystem at Arnigad improved the hydrological functioning by: reducing stormflow (82%), and enhancing: baseflow (52%), soil moisture (13%), steady infiltration rate (22%) and lag time (~15 minutes) relative to Bansigad. These enhanced values indicated soil capability to store water at forested catchment (Arnigad) and helped to understand the volume of water (discharge) that was available during dry-period. The decrease of denudation rate (at Arnigad) by 41% resulted decrease in suspended sediment (18%) and bed load (75%) compared to Bansigad. Further, the enhancement of dissolved solids in stream resulted due to maximum organic matter generated in forest floor of Arnigad. Conclusion: This study accomplishes that rainfall during the wet-period was the main driver of hydrological functioning, whereas, forests provided substantial services by regulating water balance, soil moisture and sediment budget at Arnigad catchments through different mechanisms of forest components at catchment-scale in the Central Himalayan region.

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“…Jasechko & Taylor, ; Y. Cheng et al, ). Yet despite the fact that in controlled forest removal experiments the streamflow invariably increased (Brown, Zhang, McMahon, Western, & Vertessy, ), there are numerous real‐world examples of diminished groundwater recharge and dry‐season flow after tropical deforestation—despite the lower water use of the postforest land cover (Bruijnzeel, ; Krishnaswamy et al, ; Qazi, Bruijnzeel, Rai, & Ghimire, ; Recha et al, ; Roa‐García et al, ). In other words, the “forest sponge” effect can be lost if surface infiltration conditions become critically impaired by slaking, crusting, or compaction of the soil by inappropriate land management (Bruijnzeel, ; Lacombe et al, ; Sidle et al, ).…”

Section: Discussionmentioning

confidence: 99%

Water budget and run‐off response of a tropical multispecies “reforest” and effects of typhoon disturbance

et al. 2018

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To examine claims that reforesting degraded Imperata grassland in Leyte (Philippines) made streamflow perennial again, we studied the hydrological behaviour of a 23‐year‐old mixed‐species “reforest” between June 2013 and May 2014. Typhoon Haiyan, one of the strongest events ever, caused major damage to the site in November 2013. Average daily apparent water use (ET) was 5.0 mm day−1 pretyphoon and 3.2 mm day−1 after disturbance. Corresponding ratios of period total quickflow Qq to precipitation were 16% and 44%. Quickflow volume and peak discharge increased rapidly once a threshold value of ~250 mm for soil water storage in the top 60 cm was exceeded. Before disturbance, quickflow consisted predominantly of lateral subsurface flow due to high soil hydraulic conductivities down to 60 cm. After disturbance, shallow groundwater rose regularly to within 10 cm of the surface on foot slopes, and saturation overland flow was observed during several large storms. Comparing estimated annual ET and Qq for undisturbed conditions for the reforest and a nearby degraded Imperata grassland microcatchment suggested that the extra infiltration following reforestation (~240 mm year−1) exceeded the extra ET by the reforest (100–185 mm year−1), implying a net positive trade‐off (55–140 mm year−1) and tentatively confirming local claims of improved dry‐season flow.

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Impact of forest degradation on streamflow regime and runoff response to rainfall in the Garhwal Himalaya, Northwest India

Cited by 43 publications

References 56 publications

Positive and neutral effects of forest cover on dry‐season stream flow in Costa Rica identified from Bayesian regression models with informative prior distributions

Positive and neutral effects of forest cover on dry‐season stream flow in Costa Rica identified from Bayesian regression models with informative prior distributions

Hydrological Functioning of Forested Catchments, Central Himalayan Region, India.

Water budget and run‐off response of a tropical multispecies “reforest” and effects of typhoon disturbance

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