Monitoring and Modeling of Water Environment

Quantifying the impacts of water environment and conservation for sustainability in Northern Philippines

Carlos M. Pascual, Wilson D. Balenzon, Jhona Marie G. Caraang, Lourely A. Castro, Michengel O. Ganda, and Sharon N. dela Cruz

Abstract This paper presents two case studies to quantify impacts on water environment and conservation for sustainability, such as (1) feasibility of using low-cost gravity-type drip irrigation system (LCDIS) for lettuce (Lactuca sativa) and tomato (Licopersicum esculentum) during two dry seasons from 2004-2006; and (2) re-use of greywater (such as kitchen and laundry wastewater from households) for swamp cabbage (Ipomea aquatica) under controlled environment. Field plot experiments using LCDIS revealed savings of 50% of water applied for lettuce and tomato with a yield increase up to 3 t ha during the dry season as compared to the traditional irrigation methods used by farmers. Economy of scale suggests that LCDIS is feasible for large areas planted with high value crops. For the greywater studies, after 6 weeks and thereafter, the plants reacted to the different dilutions where most plants wilted and severely injured as compared to plants cultured in lower dilution and tap waters (as control). One hundred percent (100%) survival was observed in amended greywater (lower dilution) and tap water. The foregoing results showed that there is a need to amend greywater if reused for garden agriculture and industry in the near future.

Keywords greywater, kitchen and laundry wastewater, low-cost drip irrigation system, sustainability, water environment

INTRODUCTION

Water scarcity and water pollution are some of the crucial issues in the world. One of the ways to reduce the impact of water scarcity and pollution is to expand water and wastewater reuse. Access to water supply and improved sanitation is one of key factors in improving health and economic productivity. In order to increase access to water supply, the following three elements are especially important; 1) development of new water sources; 2) prevention of water resource degradation; and 3) improvement in efficiency of water consumption. Agricultural irrigation is crucial for improving the quality and quantity of production. Worldwide, agriculture is the largest user of water; the sector has accounted for 67% of total freshwater withdrawal in the world. Therefore more efficient use of agricultural water through wastewater reuse is essential for sustainable water management. Sustainable development of our landscapes will require an economic system that supports environmental goals. There is growing demand for accountability of both taxes spent or the imposition of regulations by all government programs. Justifying spending on environmental programs or regulating land use will require demonstration of the benefits and performance of various policies and practices. This is never a simple task but is particularly challenging in the environmental world where natural weather and landscape variability can mask the best of intentions. As demand for conservation and environmental programs continues to grow, a question emerges from policy makers, agencies, interest groups, and the public: How do we measure success? How do we best communicate to the public our success? Environmentally sound technologies protect the environment, pollute less, use resources in a more sustainable manner, recycle more wastes and products, and handle residual wastes in a more acceptable manner than the technologies which they replace. Environmentally sound technologies in the context of pollution are technologies that generate low or no waste, and they may also cover end of the pipe technologies for treatment of pollution after it is generated. Environmentally sound technologies are not just individual technologies, but total systems which include know-how, procedures, goods and services, and equipment as well as organizational and managerial procedures. Some of these technologies include the drip irrigation system (Cuenca, 1989; Pascual and Dumaoal, 1999; and van Lier, 1999) for water conservation and re-use of greywater for household or garden irrigation which are often overlooked and has showed some potential uses but needs for baseline information for environmental concern (Guerrero and Guerrero, 2004). And since the cost of irrigation depends on water supply and energy resources, there is a need for an appropriate irrigation scheme for cash crops like lettuce (Lactuca sativa L) and tomato (Licopersicum esculentum).

Thus, the Case study 1 generally aimed to evaluate the performance of the low-cost gravity-type drip irrigation system under field conditions. Specifically, the study aimed to: a) determine the irrigation efficiency using gravity- type drip irrigation and furrow methods of irrigation; b) assess the growth and yield of lettuce and tomato as affected by different irrigation methods; and c) compare the economic feasibility of gravity-type drip irrigation system with the farmer's practice on lettuce and tomato. The Case study 2 aimed to ascertain the effects of greywater such as kitchen waste water (KWW) and laundry waste water (LWW) from household on swamp cabbage. Specific objectives were to: a) estimate the major chemical properties of KWW and LWW from a household; b) evaluate the effects of the level of concentration of detergent in KWW and LWW on the number of shoots, net growth and root length of swamp cabbage (Ipomea aquatica); and c) estimate the actual evapotranspiration of swamp cabbage as affected by the level of concentration of KWW and LWW.

MATERIALS AND METHODS

Case study 1

The Case study 1 was conducted at the vegetable production area of the Mariano Marcos State University Batac, Ilocos Norte, Philippines. The experiment covered total area of 200 m each and planted to lettuce and tomato, separately. The LCDIS or low-cost gravity-type drip irrigation system (US$0.48/m) was operated at constant water head of 3 meters with 20 meters length of dripperlines to simulate the steady flow rate of the emitters, which irrigated half of the area. The other half of the area was irrigated using furrow method. Each study area of 200 m was divided into two plots to represent two treatments, the drip irrigation system and furrow irrigation. The irrigation performance indicators for drip include: the coefficient of manufacturing variation (Cv) was used as a measure of the anticipated variations in discharge for emitters (Van Lier, et al., 1999); uniformity coefficient (EU) (Van Lier, et al., 1999) and application efficiency (AE). Methods used in the studies were presented by Ganda (2005) and Balenzon (2006). The height of the plants was taken from ten sample plants in each treatment with the use of a meter stick set at the base of each plant. The diameter of the head was based on the polar and equatorial diameter of the samples...