the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Water Productivity of Phoenix Metropolitan Area Cities
- School of Informatics, Computing and Cyber Systems, Northern Arizona University, Flagstaff, Arizona, USA
- School of Informatics, Computing and Cyber Systems, Northern Arizona University, Flagstaff, Arizona, USA
Abstract. Water productivity (or efficiency) data informs water policy, zoning and planning along with water allocation decisions under water scarcity pressure. This paper demonstrates that different water productivity metrics lead to different conclusions about who is using water more effectively. In addition to supporting the population's drinking and sanitation needs, water generates many other public and private social, environmental, and economic values. For the group of municipalities comprising the Phoenix Metropolitan Area we compare several water productivity metrics by calculating the Water Value Intensity (WVI) of potable water delivered by the municipality to its residential and non-residential customers. Core cities with more industrial water uses are less productive by the conventional efficiency measure of water used per capita, but core cities generate more tax revenues, business revenues, and payroll revenues per unit of water delivered, achieving a higher water productivity by these measures. We argue that policymakers should consider a more diverse set of socio-economic water productivity measures to ensure that a broader set of values are represented in water allocation policies.
Benjamin Ruddell et al.
Status: open (until 08 Mar 2023)
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RC1: 'Comment on egusphere-2022-1367', Pieter van der Zaag, 15 Jan 2023
reply
I find the topic interesting and relevant. I have four comments and a few more detailed comments.
My first comment is that I find the paper not so easy to read, although the argument of the paper is not very complex. I am therefore convinced that the presentation of the work can be much improved. I mention two points of improvements.
(a) The authors could select a reduced number of water productivity metrics that most aptly reflect the point the authors wish to make (and in supplementary materials they could include details of the other metrics considered). I base this comment on the following. Figure 3 demonstrates that two groups of each two metrics behave identically in the different locations (namely Gross Revenue and State Sales Tax, and Payroll and State Income Tax), and for the second group a third metric only deviates from its two metrics in one location (namely Net Revenue, which behaves differently only in Phoenix). If one would delve into the details of those metrics, I guess it wouldn’t be very difficult to explain why they behave identically. This would enable to simplify the paper and select the most telling metric of each group, or the one that is most easily to be collected/measured, while commenting that the other metric can also be used.
(b) The point made towards the end of section 2 could be presented more prominently, namely that different stakeholders value different metrics differently. The argument of the paper could then be weaved along these selected stakeholders. This would in my view make the paper much more easily readable and thus much more attractive.
As a side note, it remains unclear how many metrics the paper reports; in the text it is stated that they are six (line116), whereas 7 are reported in lines 116 and 117, but in lines 80-81, there are 8 metrics mentioned. But note that “net revenue” is mentioned twice in both. In figure 3, however, only 6 appear. This requires clarification.
My second comment concerns details. Some details are given in the paper, but these should either be better explained, or relegated to an appendix. I refer here to the issue of including or excluding the indirect value. I guess this is an important issue but the assumptions and implications of excluding these seem to come as an afterthought.
A third comment: I am not an economist, but I find the suggestion that all values used as metrics are all fully attributed to (or imputed to) the water input. For example, in line 202 it states: “Property taxes were used as a measure for the values produced by residential water use.” Similarly, in lines 94-95 it is stated that “Within each municipality water is allocated to Residential and Non-Residential uses, which yield residential values (income tax, property tax, population) and non-residential values (payroll, net/gross revenue, sales tax).”
But it is clear that water is only one input among many that produces this value, and often a relatively minor input compared to others.
A fourth comment refers to the statement made in the beginning of the paper in lines 49-50: “... we manage what we measure …”. This is potentially a problematic statement, as this might imply that what cannot be measured cannot be managed. And this may have a problematic relation with a remark made towards the end of the paper, namely in lines 278-280, “We omit environmental and social wellness values, from this research (…) due to a lack of quantifiable data on these measures.” Doesn’t this pose a fundamental limitation to the main purpose of this paper, namely that certain important values may not be quantifiable in water productivity metrics. I would find it interesting if the authors would include a more nuanced reflection on this issue.
More detailed comments:
The title is quite general – perhaps a subtitle could indicate what specifically the paper is about, namely that water adds different types of value that cannot easily be commensurated.
I would prefer a straightforward use of the concept of water productivity, as against the little known “water value intensity” concept.
The values of WVI presented (as in Figure 3) are, I guess, normalised values. But this is not explained in the text. Also the dimensions/units of value should be explicitly reported when values are presented.
The concept of “payroll’ may need an explanation, as not all readers may be familiar with this concept; I understand that it refers to the wage bill/salaries?
The acronyms SRP and CAP are not explained when first used (line 92), nor ADWR (line 108).
I found it confusing that one the one hand the authors explain that they use data on water withdrawals, and not data on water consumed (line 102 and lines 107-112), and that they later add L&U water (= lost and unaccounted for water) to the data on water use/water withdrawals they got from ADWR. To the reader this may seem that some double counting of water might occur. This requires an explanation.
In this same sense I think it would be wise to use one consistent term for these data: is it “water use”, “water withdrawal” or “water demand”? In the tables in Annex B the term ‘demand’ is used. But the demand for water may not be identical to the use of water, and thus not for the water withdrawals. So water demand is not entirely a correct term for the data used in this paper. I oudl recommend to choose between “water use”, “water withdrawal”.
Appendix A-1 (line 140) doesn’t exist. I guess you mean Appendix A.
Lines 156-157 state: “In this case there are six direct and local values produced, one direct impact on the local freshwater stock…” But these direct and local values and the direct impact are not made explicit. Are these the same as the (6, or 67 or 8) mentioned earlier?
Figure 3: not clear what the blue line of population signifies. What is the unit? What does a population of “1” mean?
Table 1: I don’t understand how the last two columns (“Acre feet per km2 of city” and “Acre feet per person per km2”) were calculated.
There are several sentences where a word is missing, or something else is amiss in the sentence, including in the following lines: 99, 109, 118, 129, 266, 280.
Benjamin Ruddell et al.
Benjamin Ruddell et al.
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