scholarly journals Irrigation return flow causing a nitrate hotspot and denitrification imprints in groundwater at Tinwald, New Zealand

2020 ◽  
Vol 24 (7) ◽  
pp. 3583-3601
Author(s):  
Michael Kilgour Stewart ◽  
Philippa Lauren Aitchison-Earl
Keyword(s):  
Stable Isotopes ◽  
Local Community ◽  
Economic Cost ◽  
Flow Coefficient ◽  
Organic N ◽  
Nitrate Transport ◽  
Small Scale ◽  
Return Flow ◽  
Irrigation Flow ◽  
Irrigation Return Flow

Abstract. Nitrate concentrations in groundwater have been historically high (N≥11.3 mg L−1) in an area surrounding Tinwald, Ashburton, since at least the mid-1980s. The local community is interested in methods to remediate the high nitrate in groundwater. To do this, they need to know where the nitrate is coming from. Tinwald groundwater exhibits two features stemming from irrigation with local groundwater (i.e. irrigation return flow). The first feature is increased concentrations of nitrate (and other chemicals and stable isotopes) in a “hotspot” around Tinwald. The chemical concentrations of the groundwater are increased by recirculation of water already relatively high in chemicals. The irrigation return flow coefficient C (irrigation return flow divided by irrigation flow) is found to be consistent with the chemical enrichments. The stable isotopes of the groundwater show a similar pattern of enrichment by irrigation return flow of up to 40 % and are also enriched by evaporation (causing a loss of about 5 % of the original water mass). Management implications are that irrigation return flow needs to be taken into account in modelling of nitrate transport through soil–groundwater systems and in avoiding overuse of nitrate fertiliser leading to greater leaching of nitrate to the groundwater and unnecessary economic cost. The second feature is the presence of “denitrification imprints” (shown by enrichment of the δ15N and δ18ONO3 values of nitrate) in even relatively oxic groundwaters. The denitrification imprints can be clearly seen because (apart from denitrification) the nitrate has a blended isotopic composition due to irrigation return flow and N being retained in the soil–plant system as organic N. The nitrate concentration and isotopic compositions of nitrate are found to be correlated with the dissolved oxygen (DO) concentration. This denitrification imprint is attributed to localised denitrification in fine pores or small-scale physical heterogeneity where conditions are reducing. The implication is that denitrification could be occurring where it is not expected because groundwater DO concentrations are not low.

scholarly journals Irrigation return flow causing a nitrate hot spot and denitrification imprints in groundwater at Tinwald, New Zealand

2020 ◽  
Author(s):  
Michael Kilgour Stewart ◽  
Philippa Lauren Aitchison-Earl
Keyword(s):  
Stable Isotopes ◽  
Hot Spot ◽  
Economic Cost ◽  
Flow Coefficient ◽  
Organic N ◽  
Nitrate Transport ◽  
Small Scale ◽  
Return Flow ◽  
Irrigation Flow ◽  
Irrigation Return Flow

Abstract. Tinwald groundwater exhibits two features stemming from irrigation with local groundwater (i.e. irrigation return flow). The first is increased concentrations of nitrate (and other chemicals and stable isotopes) in a hot spot around Tinwald. The chemical concentrations of the groundwater are increased by recirculation of water already relatively high in chemicals. The irrigation return flow coefficient C (irrigation return flow/irrigation flow) is found to be consistent with the chemical enrichments. The stable isotopes of the groundwater show a similar pattern of enrichment by irrigation return flow of up to 40 % and are also enriched by evaporation (causing loss of about 20 % of the original water mass). Management implications are that irrigation return flow needs to be taken into account in modelling of nitrate transport through soil/groundwater systems and in avoiding overuse of nitrate fertilizer leading to greater leaching of nitrate to the groundwater and unnecessary economic cost. The second feature is the presence of denitrification imprints (shown by enrichment of the δ15N and δ18ONO3 values of nitrate) in even relatively oxic groundwaters. The denitrification imprints can be clearly seen because (apart from denitrification) the nitrate has a blended isotopic composition due to irrigation return flow and N being retained in the soil-plant system as organic-N. The nitrate concentration and isotopic compositions of nitrate are found to be correlated with dissolved oxygen concentration. This denitrification imprint is attributed to localised denitrification in fine pores or small-scale physical heterogeneity where conditions are reducing. The implication is that denitrification could be occurring where it is not expected because groundwater DO concentrations are not low.

Fully distributed versus semi-distributed process simulation of a highly managed watershed with mixed land use and irrigation return flow

2021 ◽  
Vol 140 ◽  
pp. 105000
Author(s):  
Anoop Valiya Veettil ◽  
Timothy R. Green ◽  
Holm Kipka ◽  
Mazdak Arabi ◽  
Nathan Lighthart ◽  
...  
Keyword(s):  
Land Use ◽  
Process Simulation ◽  
Return Flow ◽  
Irrigation Return Flow ◽  
Distributed Process ◽  
Mixed Land Use

Irrigation return flow and nutrient movement mitigation by irrigation method for container plant production

2021 ◽  
Author(s):  
Damon E. Abdi ◽  
James S. Owen ◽  
Julie C. Brindley ◽  
Anna Birnbaum ◽  
Bert M. Cregg ◽  
...  
Keyword(s):  
Plant Production ◽  
Return Flow ◽  
Irrigation Method ◽  
Irrigation Return Flow ◽  
Container Plant

scholarly journals Stakeholder consultations on small-scale irrigation schemes’ constraints in Zimbabwe

2021 ◽  
Author(s):  
Edgar Muhoyi ◽  
Josue Mbonigaba
Keyword(s):  
Local Community ◽  
Theory Of Constraints ◽  
Small Scale ◽  
Focus Group Discussions ◽  
Group Discussions ◽  
Key Informant ◽  
Technical Issues ◽  
Social Environmental ◽  
Political Economic ◽  
Small Scale Irrigation

AbstractSmall-scale irrigation schemes (SSIS) have been considered a solution to viability challenges in drought-stricken farming areas in developing countries. However, the schemes face severe constraints. In this paper, relevant constraints are identified and ranked in terms of how serious the limitations are from the perspective of stakeholders in drought-prone areas of the Chipinge District in Zimbabwe. Information for the study was gained through a questionnaire and focus group discussions with small-scale irrigation farmers as well as key informant interviews with government irrigation officials, irrigation managers and members of the local community leadership. The information was garnered between August and December in 2017 with the analysis conducted using descriptive statistics and thematic analysis, guided by the Theory of Constraints and classified in the political, economic, social, technological, environmental and legal (PESTEL) framework. Results indicated that SSIS are important in the drought-prone areas of the Chipinge District regarding food security and income generation. However, technical issues bedevilling the schemes are considered to be the most challenging limitations. The most important constraints—ranked in descending order of gravity—are technical, economic, social, environmental, legal and political challenges. Based on these findings, the research strongly recommends modernising small-scale irrigation schemes’ infrastructure, among other issues, as a priority in Zimbabwe's drought-prone areas.

scholarly journals Collaborative configurations of tourism development: a Greenlandic example

2019 ◽  
Vol 6 (1) ◽  
pp. 24-39
Author(s):  
Daniela Chimirri
Keyword(s):  
Design Methodology ◽  
Local Community ◽  
Tourism Development ◽  
Essential Element ◽  
Small Scale ◽  
Research Approach ◽  
Content Type ◽  
Study Approach ◽  
Collaborative Activities

Purpose While tourism scholars have increasingly recognized the significance of collaboration as an essential element in tourism development, there is a lack of theoretical and empirical research centering on (trans)local collaboration as a central means for future tourism development in Greenland. The purpose of this paper is to analyze the conceptual and analytic potentials and challenges of collaboration in an explorative case study. Design/methodology/approach The paper applies a case study approach to scrutinize collaboration in the setting of a tourism workshop in South Greenland. This research approach is exploratory in nature and focuses on collaborative activities among participants from different research institutions and countries, from Campus Kujalleq in Qaqortoq, from small-scale enterprises and businesses, managers of destination marketing organizations and local fishermen. Findings Four “collaborative configurations” emerged during the workshop. These inspire and challenge ways of (re)conceptualizing collaborative tourism development in South Greenland and call for the reconsideration of the present approach toward tourism development for shaping new possible future(s) of tourism in the Greenlandic context. Originality/value The relevance of this paper emerges from the crucial significance that tourism actors in Greenland credit collaboration. Moreover, by approaching development issues from within and mutually developing possible practice solutions through collaboration with local tourism actors, the paper aims to give voice to the local community, which currently is lacking in the debate on tourism development in Greenland.

scholarly journals Environmental Surveillance Can Dynamically Track Ecological Changes in Enteroviruses

2019 ◽  
Vol 85 (24) ◽  
Author(s):  
Hiroki Ozawa ◽  
Hiromu Yoshida ◽  
Shuzo Usuku
Keyword(s):  
Multidimensional Scaling ◽  
Large Scale ◽  
Local Community ◽  
Amino Acid Sequences ◽  
Time Dependent ◽  
Small Scale ◽  
Dependent Manner ◽  
Environmental Surveillance ◽  
Ecological Changes ◽  
Over Time

ABSTRACT Environmental surveillance can be used to trace enteroviruses shed from human stool using a sewer network that is independent of symptomatic or asymptomatic infection. In this study, the local transmission of enteroviruses was analyzed using two wastewater treatment plants, which were relatively close to each other (15 km), designated as sentinels. Influent was collected at both sentinels once a month from 2013 to 2016, and viruses were isolated. Using neutralizing tests with type-specific polyclonal antisera and molecular typing, 933 isolates were identified as enteroviruses. Our results showed that the frequency of virus isolation varied for each serotype at the two sentinels in a time-dependent manner. Because echovirus 11 (Echo11) and coxsackievirus B5 isolates showed a high frequency and were difficult to distinguish, they were further grouped into various lineages based on the VP1 amino acid sequences. The prevalence of each lineage was visualized using multidimensional scaling. The results showed that Echo11 isolates of the same lineage were isolated continuously, similar to coxsackievirus B5 isolates of three lineages. Conversely, Echo1, Echo13, Echo18, Echo19, Echo20, Echo29, and Echo33 were isolated only once each. Our findings suggested that if an enterovirus is imported into the population, it may result in small-scale transmission, whereas if there are initially many infected individuals, it may be possible for the virus to spread to a wide area, beyond the local community, over time. In addition, our findings could provide insights into risk assessment of transmission for importation of poliovirus in polio-free countries and regions. IMPORTANCE In this study, we showed that environmental enterovirus surveillance can be used to monitor the propagation of nonpolio enteroviruses in addition to poliovirus detection. Since epidemiological studies of virus transmission based on the past were performed using specimens from humans, there were limitations to research design, such as specimen collection for implementation on a large-scale target population. However, environmental monitoring can dynamically track the ecological changes in enteroviruses in the region by monitoring viruses in chronological order and targeting the population within the area by monitoring viruses over time. We observed differences in the transmission of echovirus 11 and coxsackievirus B5 in the region according to lineage in a time-dependent manner and with a multidimensional scaling pattern.

Predicting Irrigation Return Flow Rates

1978 ◽  
Vol 21 (6) ◽  
pp. 1142-1143
Author(s):  
J. A. Bondurant ◽  
C. E. Brockway ◽  
M. J. Brown
Keyword(s):  
Return Flow ◽  
Flow Rates ◽  
Irrigation Return Flow
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