Land use effect and hydrological control on nitrate yield in subtropical mountainous watersheds

Huang, Jr‐Chuan; Lee, Tsung-Yu; Kao, Shuh‐Ji; Hsu, Shih Chieh; Lin, Hsing‐Juh; Peng, Tsung-Ren

doi:10.5194/hess-16-699-2012

Cited by 55 publications

(44 citation statements)

References 66 publications

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“…During the wet season, the average daily discharges are 11.80 and 4.07 m 3 s −1 , respectively. The study watersheds represent the typical landscape in mountainous regions (i.e., small proportion of agricultural activities located along the riparian zone) where some of the residents earn their living by growing vegetables and fruits (Huang et al, 2012b). The land use pattern and the landscape characteristics for each catchment are shown in Fig.…”

Section: Study Sitementioning

confidence: 99%

“…The excess fertilization is also due to loss of N during the wet season. Based on watershed monitoring network in our study area and a sophisticated deconvolution method, Huang et al (2012b) demonstrated a very high nitrate yield number from active farms, ∼ 3000 kg N ha −1 yr −1 , which was the apparent major contributor to enhanced nitrate in stream water. A 1 % increment of active farm land use yields an increase in DIN y from background (∼ 8.3 kg N ha −1 yr −1 ) to ∼ 38 kg N ha −1 yr −1 .…”

Section: Importance Of Human Activity On Nutrient Exportmentioning

confidence: 99%

“…Although the Yusheng Creek watershed has only 8.9 % agriculture land, which is not intensive at all when compared to the cultivated extent in the Continents, this watershed has a low water quality index and degradation in benthic algae biodiversity (Yu et al, 2005). Moreover, the mountainous watersheds are more sensitive to farming activity (Huang et al, 2012b) where even a small percentage of cultivation is influential, particularly for the high water quality demand of the upstream biome.…”

Section: Study Sitementioning

confidence: 99%

“…During May to October, the season of growing and fertilizer application for agriculture, 3-5 typhoons strike Taiwan, increasing episodic runoff facilitating high erosion and nutrient export to the aquatic system. In headwater catchments, agriculture-associated land use is limited by government rules, yet nutrient export is extremely sensitive to the runoff and land use type coverage (Huang et al, 2012b).…”

Section: T-y Lee Et Al: Temporal Variation Of Nitrate and Phosphatmentioning

confidence: 99%

“…The expropriated vegetable farms were categorized as inactive farms in this study. On the other hand, the currently producing farms, mainly cabbage, are designated as active farms (Huang et al, 2012b). The three adjacent creeks have similar environmental features, i.e., precipitation, atmospheric deposition, and geology, with varying cultivation gradients providing us a good experimental ground to explore Water samples include typhoon (red triangle) and non-typhoon (black circle) samples.…”

Section: Study Sitementioning

confidence: 99%

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Temporal variation of nitrate and phosphate transport in headwater catchments: the hydrological controls and land use alteration

et al. 2013

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Oceania rivers are hotspots of DIN (dissolved inorganic nitrogen) and DIP (dissolved inorganic phosphorus) transport due to humid/warm climate, typhoon-induced episodic rainfall and high tectonic activity that create an environment favorable for high/rapid runoff and soil erosion. In spite of its uniqueness, effects of hydrologic controls and land use on the transport behaviors of DIN and DIP are rarely documented. A 2 yr monitoring study for DIN and DIP from three headwater catchments with different cultivation gradient (0 To 8.9%) was implemented during a ~ 3 day interval with an additional monitoring campaign at a 3 h interval during typhoon periods. Results showed the DIN yields in the pristine, moderately cultivated (2.7%), and intensively cultivated (8.9%) watersheds were 8.3, 26, and 37 kg N ha⁻¹ yr⁻¹, respectively. For the DIP yields, they were 0.36, 0.35, and 0.56 kg P ha⁻¹ yr⁻¹, respectively. Higher year-round DIN concentrations and five times larger in DIN yields in intensively cultivated watersheds indicate DIN is more sensitive to land use changes. The high background DIN yield from the relatively pristine watershed was likely due to high atmospheric nitrogen deposition and large subterranean N pool. The correlations between runoff and concentration reveals that typhoon floods purge out more DIN from the subterranean reservoir, i.e., soil, by contrast, runoff washes off surface soil resulting in higher suspended sediment with higher DIP. Collectively, typhoon runoff contributes 20–70% and 47–80%, respectively, to the annual DIN and DIP exports. The DIN yield to DIP yield ratio varied from 97 to 410, which is higher than the global mean of ~ 18. Such a high ratio indicates a P-limiting condition in stream and the downstream aquatic environment. Based on our field observation, we constructed a conceptual model illustrating different remobilization mechanisms for DIN and DIP from headwaters in a mountainous river, which is analogous to typical Oceania rivers and the headwater of large rivers in similar climate zones. Our study advanced our understanding about the role of cyclones, which exert hydrological control, and land use on nutrient export in the Oceania region, benefiting watershed management under the context of climate change

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Section: Study Sitementioning

confidence: 99%

Section: Importance Of Human Activity On Nutrient Exportmentioning

confidence: 99%

Section: Study Sitementioning

confidence: 99%

Section: T-y Lee Et Al: Temporal Variation Of Nitrate and Phosphatmentioning

confidence: 99%

Section: Study Sitementioning

confidence: 99%

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Temporal variation of nitrate and phosphate transport in headwater catchments: the hydrological controls and land use alteration

et al. 2013

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Robust optimal diversion of agricultural drainage water from tea plantations to paddy fields during rice growing seasons and non-rice growing seasons

Mabaya

Unami

Yoshioka

et al. 2015

Paddy Water Environ

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We investigated seasonal water quality changes on different land uses in a small agricultural watershed dominated with rice and tea crops. Observed NO 3 -N in tea plantations and tea drainage channels was sufficiently high enough to cause downstream water pollution throughout the year. On contrary, significant NO 3 -N reductions were observed in abandoned and active paddy fields, and were highest in active paddy fields during rice growing seasons. Accordingly, a question is posed whether deliberately diverting NO 3 -N contaminated drainage water from tea plantations to paddy fields would be effective a strategy for reducing downstream water pollution. NO 3 -N ratios reduced in paddy fields are however neither distinct nor known in advance, and this uncertainty could consequently lead to further environmental risks like NO 3 -N leaching and production of greenhouse N 2 O gas. We assume that NO 3 -N reduction rates of paddy fields and drainage canals are constrained in an ellipsoidal set of uncertainty. A portfolio optimisation problem is formulated to determine optimal rates of diversion from tea drainage channel into paddy fields. The problem is numerically solved in robust optimisation approach by maximising minimum NO 3 -N reduced under uncertainty. An application demonstrated that robust approach allocates different optimal rates of diversion to hedge the risk of possible malfunctioning of NO 3 -N reduction processes. Overall worst-case NO 3 -N reduction is highest in rice growing season, due to increased drainage water allocations to active paddy fields. The robust optimisation approach has potential to support decision-making processes for reducing NO 3 -N pollution and water demand pressure on water resources, and cost of rice production thereof.

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Origins of Particulate Organic Matter Determined from Nitrogen Isotopic Composition and C/N Ratio in the Highly Eutrophic Danshuei Estuary, Northern Taiwan

Gong

Cheng

et al. 2016

Aquat Geochem

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The Danshuei River flows through the heavily populated metropolitan area of Taipei and New Taipei cities, which causes remarkable additions of nutrient elements. In spite of the rather short residence time of water, the Danshuei estuary is distinctive for the very high ammonium concentration and extensive hypoxia in its lower reach. Because particulate organic matter (POM) is potentially the culprit of hypoxia, we investigate the isotopic characteristics of POM collected in February and July 2009 at a fixed station over four semidiurnal tidal cycles. By using nitrogen isotopic composition and C/N ratio of POM, we derive the relative contributions of POM from different sources. One potential source that combines dead and living phytoplankton, phytodetritus, has d 15 N values that can be predicted by the d 15 N of ammonium and the isotope effect during ammonium uptake; however, the isotope effect is concentration dependent. We employ a three-endmember mixing model based on d 15 N and C/N ratio to calculate the fractional contributions from three major POM sources, i.e., phytodetritus, soil, and sediment. Sensitivity test was conducted for the derivations from both carbon and nitrogen basis. For February 2009 we found the three fractions (in terms of contribution to the particulate organic carbon) to be 45 ± 19, 10 ± 11 and 45 ± 13 %, respectively; for July 2009, 71 ± 18, 11 ± 10 and 18 ± 13 %, respectively. The results imply that phytodetritus is probably the major culprit for the hypoxic conditions in the estuary, especially, in summer. K. K. Liu: Deceased on 12 August 2015. Electronic supplementary material The online version of this article (

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Land use effect and hydrological control on nitrate yield in subtropical mountainous watersheds

Cited by 55 publications

References 66 publications

Temporal variation of nitrate and phosphate transport in headwater catchments: the hydrological controls and land use alteration

Temporal variation of nitrate and phosphate transport in headwater catchments: the hydrological controls and land use alteration

Robust optimal diversion of agricultural drainage water from tea plantations to paddy fields during rice growing seasons and non-rice growing seasons

Origins of Particulate Organic Matter Determined from Nitrogen Isotopic Composition and C/N Ratio in the Highly Eutrophic Danshuei Estuary, Northern Taiwan

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