Novo 1*, M.E.; Oliveira2, L.; Henriques3, M.J.; Lobo Ferreira4, J.P.
1LNEC, Portugal, e-mail: enovo@lnec.pt 2LNEC, Portugal, e-mail: lgsoliveira@gmail.com
3LNEC, Portugal, e-mail: mjhenriques@lnec.pt 4LNEC, Portugal, e-mail: lferreira@lnec.pt
Abstract
Under the study PROWATERMAN a methodology to identify regions in a watershed demanding priority intervention in order to recover the good status of water bodies, as demanded by the Water Directive of the EU, was developed. The methodology takes into account the type of water body due to be recovered, the distribution and loads of the pollution sources, human settlings and soil occupation and its related pollution sources and water bodies in hydraulic connection with the water body to be recovered. In order to have a broad scope of application, this methodology was developed for: (1) surface waters, (2) groundwater. Its end result is a zonation of priority areas for intervention, which, in the case study is translated in 2 maps: (1) priority areas to control pollution from reaching the surface waters by surface discharges, (2) priority areas to control pollution from reaching the surface waters by groundwater discharges. This zonation classifies the areas from “Immediate Priority for intervention” to “Very Low Priority for intervention”.
Keywords: Recovery of surface water environments; groundwater-surface waters connections; intervention priority index
Resumo
No estudo PROWATERMAN foi desenvolvida uma metodologia para identificar regiões numa bacia hidrográfica que sejam prioritárias para intervenção para a recuperação do estado bom das massas de água, em conformidade com a Directiva da Água. A metodologia considera o tipo de massa de água a ser recuperada, a distribuição das cargas polu- entes, a ocupação do solo e fontes de poluição associadas, assim como as massas de água em conexão hidráulica com a massa de água a recuperar. De modo a ter um amplo campo de aplicação, esta metodologia foi desenvolvida para massas de água superficiais e subterrâneas. O seu resultado final é um mapa de zonamento de prioridades de intervenção, o que no caso de estudo é traduzido por dois mapas: (1) áreas prioritárias para controlar a poluição que atinge as águas superficiais a partir de fontes superficiais, (2) áreas prioritárias para controlar a poluição que atinge as águas superficiais a partir das descargas de águas subterrâneas.
Palavras-chave: Recuperação de ecossistemas aquáticos superficiais; Interacções águas superficiais- subterrâenas; índex de prioridade de intervenção.
40 Introduction
The requirement stemming from the Water Directive to restore water bodies’ Good status in its quantitative and qualitative components, until 2027 at the latest, de- mands for each case the identification of the best intervention measures and the areas which shall have the first interven- tions, with the minimum expenditure while obtaining the best results. As such recovery measures and priority intervention areas were such measures should be applied must be identified. Under the aegis of PROWATERMAN study a methodology to identify priority areas requiring recovery measures due to recover water bodies un- der poor status was developed. Although this methodology was developed for Melides watershed, it was developed under a broader mindset, being designed to ac- count for most situations found in a water- shed. Melides watershed has a small area and the river network has its mouth in Melides coastal lagoon; the underlying aq- uifer feeds .the river network, which dis- charges into the lagoon carrying along the pollution loads generated in the watershed. The methodology is SIG based and was developed with a structure somehow similar to DRASTIC [1], incorporating elements of IFI methodology [3] and the data gathered by PROWATERMAN study [2]. It has two independent components: (1) priority areas for intervention upon surface water environ- ments, (2) priority areas for intervention up- on groundwater. Such approach was adopt- ed because in the study area the surface water bodies’ status depends on the aquifer status; at the same time this methodology was envisioned for application on a wide range of situations and water environments. Where there is hydraulic connection be- tween surface and groundwater and both are in status lesser than Good, intervention priority areas must be defined for both envi- ronments; when only surface water envi- ronments are in status lesser than Good and/or there is no hydraulic connection with groundwater, only the surface component of the methodology shall be used; where aqui- fer has status lesser than Good and/or there are no hydraulic connection with surface water environments, only the groundwater component shall be applied. For surface
waters priority intervention are located around the lower reaches’ margins of Melidesd creek, while for groundwaters, they are concentrated around the same area main groundwater pollution sources (e.g. Camping Park, livestock units).
Material and Methods
The methodology is index-based, uses SIG tools and generates a set of maps for each parameter, being their intersection (sum of all parameters) the final Priority Intervention Index map for each of the two independent components: (1) priority intervention upon surface water environments, (2) priority in- tervention upon groundwater.
For the Priority Intervention Index for surface waters (Table 1), the index is calculated through the formula:
IPSup = 3 x DSup + 2 x NfSup + 3 x CSup + 1
x ZdSup
Being IPSup = Surface-waters intervention
priority index, DSup = Distance to the water
body, NfSup = Spatial distribution of pollu-
tion sources, CSup = Pollution loads, ZdSup
= Discharge zones to surface waters, the respective parameters for this index.
Table 1 – Intervention Priority Index for surface-waters
Index InterventionPriority > 100 Immediate 75 – 100 Urgent 55 – 75 Moderate 37 – 54 Low 25 – 36 VeryLow 8 – 24 No actionrequired
For the Priority Intervention Index for groundwater (Table 2), the index is calcu- lated through the formula:
IPSubt = 3 x DSubt + 2 x NfSubt + 3 x CSubt +
3 x TPSubt + 4 x IFI + 1 x ZdSubt
Being IPSubt = Groundwater intervention
priority index, DSubt = Depth to the water
table, NfSubt = Spatial distribution of pollu-
tion sources, CSubt = Pollution loads, TPSubt
= Travel time, IFI = IFI index, ZdSubt
=Discharge zones to surface waters the respective parameters for this index.
Table 2 – Intervention Priority Index for groundwater Index InterventionPriority 189 – 270 Immediate 149 – 188 Urgent 112 – 148 Moderate 76 – 111 Low 24 – 75 VeryLow
Results and Conclusions
The results from this methodology are presented in Figure 1 for intervention are- as concerning surface waters and in Fig- ure 2 for intervention areas concerning groundwater. Areas in read are those with higher priority of intervention and dark
Figure 1 – Surface-water Priority Index.
green ones those demanding very low priority to no intervention at all. As shown in the Figures, upper reaches of the wa- tershed have little to no priority interven- tion while the areas along Melides lagoon
and the lower reaches of Melides creek are those demanding the higher priority, and as such should be the main and first ones demanding recovery measures.
Figure 2 – Groundwater Priority Index.
Acknowledgments
This work was supported by FCT under the project PTDC/AAC-AMB/105061/2008
Bibliography
[1] Aller, L., Bennet, T., Leher, J. H., Petty, R., Hackett, G. (1987), DRASTIC: A Standardized System for Evalu- ating Ground Water Pollution Potential Using Hydro- geological Settings. U.S. EnvironmentalProtectionA- gency, pp. 622.
[2] Novo, M.E., Oliveira, L., Henriques, M.J. (2013), Água, ecossistemas Aquáticos e Actividade Humana – Pro- jecto PROWATERMAN. Estratégias e medidas de gestão dos recursos hídricos da bacia de Melides (quantidade e qualidade química e biológica) em ce- nários sócio-económicos e de alterações climáticas. Relatório 128/2013 – DHA/NAS, pp. 278.
[3] Oliveira, M.M., Lobo Ferreira, J.P. (2002), Proposta de uma Metodologia para a Definição de Áreas de Infil- tração Máxima. Associação Portuguesa dos Recur- sos Hídricos, Revista Recursos Hídricos, Vol. 23 n.º 1, Maio 2002 pp. 63-74.